diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 8e388fd6b..31497815c 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -39,7 +39,7 @@ import ContentLinkShare from '@/components/home/ContentLinkShare.vue'
 import NoAuthWrapper from '@/components/misc/NoAuthWrapper.vue'
 import Ready from '@/components/misc/Ready.vue'
 
-import {setLanguage} from '@/i18n'
+import {setLanguage, getBrowserLanguage} from '@/i18n'
 
 import {useAuthStore} from '@/stores/auth'
 import {useBaseStore} from '@/stores/base'
@@ -88,7 +88,7 @@ watch(userEmailConfirm, (userEmailConfirm) => {
 	router.push({name: 'user.login'})
 }, { immediate: true })
 
-setLanguage(authStore.settings.language)
+setLanguage(authStore.settings.language ?? getBrowserLanguage())
 useColorScheme()
 </script>
 
diff --git a/frontend/src/components/base/BaseButton.story.vue b/frontend/src/components/base/BaseButton.story.vue
index 784d1bc1a..a0d68587c 100644
--- a/frontend/src/components/base/BaseButton.story.vue
+++ b/frontend/src/components/base/BaseButton.story.vue
@@ -1,10 +1,10 @@
 <script lang="ts" setup>
 import {logEvent} from 'histoire/client'
-import {reactive} from 'vue'
+import {reactive, type App} from 'vue'
 import {createRouter, createMemoryHistory} from 'vue-router'
 import BaseButton from './BaseButton.vue'
 
-function setupApp({ app }) {
+function setupApp({ app }: { app: App }) {
   // Router mock
   app.use(createRouter({
     history: createMemoryHistory(),
diff --git a/frontend/src/components/base/Expandable.vue b/frontend/src/components/base/Expandable.vue
index 5286ba8ed..f56f0100d 100644
--- a/frontend/src/components/base/Expandable.vue
+++ b/frontend/src/components/base/Expandable.vue
@@ -83,47 +83,51 @@ function forceLayout(el: HTMLElement) {
 # see: https://vuejs.org/guide/built-ins/transition.html#javascript-hooks
 ###################################################################### */
 
-function beforeEnter(el: HTMLElement) {
-  el.style.height = '0'
-  el.style.willChange = 'height'
-  el.style.backfaceVisibility = 'hidden'
-  forceLayout(el)
+function beforeEnter(el: Element) {
+  const element = el as HTMLElement
+  element.style.height = '0'
+  element.style.willChange = 'height'
+  element.style.backfaceVisibility = 'hidden'
+  forceLayout(element)
 }
 
 // the done callback is optional when
 // used in combination with CSS
-function enter(el: HTMLElement) {
-  const height = getHeight(el) // Get the natural height
-  el.style.height = height // Update the height
+function enter(el: Element) {
+  const element = el as HTMLElement
+  const height = getHeight(element) // Get the natural height
+  element.style.height = height // Update the height
 }
 
-function afterEnter(el: HTMLElement) {
-  removeHeight(el)
+function afterEnter(el: Element) {
+  removeHeight(el as HTMLElement)
 }
 
-function enterCancelled(el: HTMLElement) {
-  removeHeight(el)
+function enterCancelled(el: Element) {
+  removeHeight(el as HTMLElement)
 }
 
-function beforeLeave(el: HTMLElement) {
+function beforeLeave(el: Element) {
+  const element = el as HTMLElement
   // Give the element a height to change from
-  el.style.height = `${el.scrollHeight}px`
-  forceLayout(el)
+  element.style.height = `${element.scrollHeight}px`
+  forceLayout(element)
 }
 
-function leave(el: HTMLElement) {
+function leave(el: Element) {
+  const element = el as HTMLElement
   // Set the height back to 0
-  el.style.height = '0'
-  el.style.willChange = ''
-  el.style.backfaceVisibility = ''
+  element.style.height = '0'
+  element.style.willChange = ''
+  element.style.backfaceVisibility = ''
 }
 
-function afterLeave(el: HTMLElement) {
-  removeHeight(el)
+function afterLeave(el: Element) {
+  removeHeight(el as HTMLElement)
 }
 
-function leaveCancelled(el: HTMLElement) {
-  removeHeight(el)
+function leaveCancelled(el: Element) {
+  removeHeight(el as HTMLElement)
 }
 
 function removeHeight(el: HTMLElement) {
diff --git a/frontend/src/helpers/parseDateOrNull.ts b/frontend/src/helpers/parseDateOrNull.ts
index 680a5bb25..4be315f13 100644
--- a/frontend/src/helpers/parseDateOrNull.ts
+++ b/frontend/src/helpers/parseDateOrNull.ts
@@ -1,7 +1,7 @@
 /**
  * Make date objects from timestamps
  */
-export function parseDateOrNull(date: string | Date) {
+export function parseDateOrNull(date: string | Date | null | undefined) {
 	if (date instanceof Date) {
 		return date
 	}
diff --git a/frontend/src/modelTypes/IAvatar.ts b/frontend/src/modelTypes/IAvatar.ts
index f9031810a..645fbc25b 100644
--- a/frontend/src/modelTypes/IAvatar.ts
+++ b/frontend/src/modelTypes/IAvatar.ts
@@ -1,6 +1,6 @@
 import type {IAbstract} from './IAbstract'
 
-export type AvatarProvider = 'default' | 'initials' | 'gravatar' | 'marble' | 'upload'
+export type AvatarProvider = 'default' | 'initials' | 'gravatar' | 'marble' | 'upload' | 'ldap'
 
 export interface IAvatar extends IAbstract {
 	avatarProvider: AvatarProvider
diff --git a/frontend/src/modelTypes/ICaldavToken.ts b/frontend/src/modelTypes/ICaldavToken.ts
index afe14b11a..0792d3f11 100644
--- a/frontend/src/modelTypes/ICaldavToken.ts
+++ b/frontend/src/modelTypes/ICaldavToken.ts
@@ -1,7 +1,12 @@
 import type {IAbstract} from './IAbstract'
 
 export interface ICaldavToken extends IAbstract {
-	id: number;
+        id: number;
 
-	created: Date;
+        created: Date;
+
+       /**
+        * The actual token value is only returned when creating a new token.
+        */
+       token?: string;
 }
diff --git a/frontend/src/modelTypes/IUser.ts b/frontend/src/modelTypes/IUser.ts
index d57d66acf..a813e6e07 100644
--- a/frontend/src/modelTypes/IUser.ts
+++ b/frontend/src/modelTypes/IUser.ts
@@ -21,6 +21,7 @@ export interface IUser extends IAbstract {
 	updated: Date
 	settings: IUserSettings
 
-	isLocalUser: boolean
-	deletionScheduledAt: string | Date | null
+        isLocalUser: boolean
+        deletionScheduledAt: string | Date | null
+        authProvider?: string
 }
diff --git a/frontend/src/models/apiTokenModel.ts b/frontend/src/models/apiTokenModel.ts
index a23227004..237074e86 100644
--- a/frontend/src/models/apiTokenModel.ts
+++ b/frontend/src/models/apiTokenModel.ts
@@ -5,9 +5,9 @@ export default class ApiTokenModel extends AbstractModel<IApiToken> {
 	id = 0
 	title = ''
 	token = ''
-	permissions = null
-	expiresAt: Date = null
-	created: Date = null
+       permissions = {}
+       expiresAt: Date = new Date()
+       created: Date = new Date()
 	
 	constructor(data: Partial<IApiToken> = {}) {
 		super()
diff --git a/frontend/src/views/teams/EditTeam.vue b/frontend/src/views/teams/EditTeam.vue
index c557de2bf..f09998e53 100644
--- a/frontend/src/views/teams/EditTeam.vue
+++ b/frontend/src/views/teams/EditTeam.vue
@@ -271,6 +271,7 @@ import User from '@/components/misc/User.vue'
 import TeamService from '@/services/team'
 import TeamMemberService from '@/services/teamMember'
 import UserService from '@/services/user'
+import UserModel from '@/models/user'
 
 import {RIGHTS as Rights} from '@/constants/rights'
 
@@ -305,8 +306,8 @@ const userService = ref<UserService>(new UserService())
 const team = ref<ITeam>()
 const teamId = computed(() => Number(route.params.id))
 const memberToDelete = ref<ITeamMember>()
-const newMember = ref<IUser>()
-const foundUsers = ref<IUser[]>()
+const newMember = ref<IUser | null>(null)
+const foundUsers = ref<IUser[]>([])
 
 const showDeleteModal = ref(false)
 const showUserDeleteModal = ref(false)
@@ -331,22 +332,22 @@ async function save() {
 	}
 	showErrorTeamnameRequired.value = false
 
-	team.value = await teamService.value.update(team.value)
+       team.value = await teamService.value.update(team.value as ITeam)
 	success({message: t('team.edit.success')})
 }
 
 async function deleteTeam() {
-	await teamService.value.delete(team.value)
+       await teamService.value.delete(team.value as ITeam)
 	success({message: t('team.edit.delete.success')})
 	router.push({name: 'teams.index'})
 }
 
 async function deleteMember() {
 	try {
-		await teamMemberService.value.delete({
-			teamId: teamId.value,
-			username: memberToDelete.value.username,
-		})
+               await teamMemberService.value.delete({
+                       teamId: teamId.value,
+                       username: memberToDelete.value?.username ?? '',
+               } as unknown as ITeamMember)
 		success({message: t('team.edit.deleteUser.success')})
 		await loadTeam()
 	} finally {
@@ -360,11 +361,11 @@ async function addUser() {
 		showMustSelectUserError.value = true
 		return
 	}
-	await teamMemberService.value.create({
-		teamId: teamId.value,
-		username: newMember.value.username,
-	})
-	newMember.value = null
+       await teamMemberService.value.create({
+               teamId: teamId.value,
+               username: newMember.value!.username,
+       } as unknown as ITeamMember)
+       newMember.value = null
 	await loadTeam()
 	success({message: t('team.edit.userAddedSuccess')})
 }
@@ -393,16 +394,16 @@ async function findUser(query: string) {
 		return
 	}
 
-	const users = await userService.value.getAll({}, {s: query})
-	foundUsers.value = users.filter((u: IUser) => u.id !== userInfo.value.id)
+       const users = await userService.value.getAll(new UserModel(), {s: query})
+       foundUsers.value = users.filter((u: IUser) => u.id !== userInfo.value?.id)
 }
 
 async function leave() {
 	try {
-		await teamMemberService.value.delete({
-			teamId: teamId.value,
-			username: userInfo.value.username,
-		})
+               await teamMemberService.value.delete({
+                       teamId: teamId.value,
+                       username: userInfo.value?.username ?? '',
+               } as unknown as ITeamMember)
 		success({message: t('team.edit.leave.success')})
 		await router.push({name: 'home'})
 	} finally {
diff --git a/frontend/src/views/teams/ListTeams.vue b/frontend/src/views/teams/ListTeams.vue
index 0189c4ade..d0c6994d2 100644
--- a/frontend/src/views/teams/ListTeams.vue
+++ b/frontend/src/views/teams/ListTeams.vue
@@ -41,6 +41,7 @@
 
 <script setup lang="ts">
 import {ref, shallowReactive} from 'vue'
+import type { ITeam } from '@/modelTypes/ITeam'
 import { useI18n } from 'vue-i18n'
 
 import TeamService from '@/services/team'
@@ -49,7 +50,7 @@ import { useTitle } from '@/composables/useTitle'
 const { t } = useI18n({useScope: 'global'})
 useTitle(() => t('team.title'))
 
-const teams = ref([])
+const teams = ref<ITeam[]>([])
 const teamService = shallowReactive(new TeamService())
 teamService.getAll().then((result) => {
 	teams.value = result
diff --git a/frontend/src/views/user/Login.vue b/frontend/src/views/user/Login.vue
index 74b254834..ac673f740 100644
--- a/frontend/src/views/user/Login.vue
+++ b/frontend/src/views/user/Login.vue
@@ -208,16 +208,23 @@ const validateUsernameField = useDebounceFn(() => {
 const needsTotpPasscode = computed(() => authStore.needsTotpPasscode)
 const totpPasscode = ref<HTMLInputElement | null>(null)
 
+interface Credentials {
+       username: string | undefined
+       password: string
+       longToken: boolean
+       totpPasscode?: string
+}
+
 async function submit() {
-	errorMessage.value = ''
+       errorMessage.value = ''
 	// Some browsers prevent Vue bindings from working with autofilled values.
 	// To work around this, we're manually getting the values here instead of relying on vue bindings.
 	// For more info, see https://kolaente.dev/vikunja/frontend/issues/78
-	const credentials = {
-		username: usernameRef.value?.value,
-		password: password.value,
-		longToken: rememberMe.value,
-	}
+       const credentials: Credentials = {
+               username: usernameRef.value?.value,
+               password: password.value,
+               longToken: rememberMe.value,
+       }
 
 	if (credentials.username === '' || credentials.password === '') {
 		// Trigger the validation error messages
diff --git a/frontend/src/views/user/PasswordReset.vue b/frontend/src/views/user/PasswordReset.vue
index d11098a9b..a9d67e29b 100644
--- a/frontend/src/views/user/PasswordReset.vue
+++ b/frontend/src/views/user/PasswordReset.vue
@@ -30,10 +30,11 @@
 					class="label"
 					for="password"
 				>{{ $t('user.auth.password') }}</label>
-				<Password
-					@submit="resetPassword"
-					@update:modelValue="v => credentials.password = v"
-				/>
+                                <Password
+                                        :model-value="credentials.password"
+                                        @submit="resetPassword"
+                                        @update:modelValue="v => credentials.password = v"
+                                />
 			</div>
 
 			<div class="field is-grouped">
@@ -85,9 +86,9 @@ async function resetPassword() {
 	}
 
 	const passwordReset = new PasswordResetModel({newPassword: credentials.password, token: token})
-	try {
-		const {message} = await passwordResetService.resetPassword(passwordReset)
-		successMessage.value = message
+       try {
+       const {message} = await passwordResetService.resetPassword(passwordReset) as unknown as {message: string}
+               successMessage.value = message
 	} catch (e) {
 		errorMsg.value = e.response.data.message
 	}
diff --git a/frontend/src/views/user/Register.vue b/frontend/src/views/user/Register.vue
index 382254283..9e9626435 100644
--- a/frontend/src/views/user/Register.vue
+++ b/frontend/src/views/user/Register.vue
@@ -72,11 +72,12 @@
 					class="label"
 					for="password"
 				>{{ $t('user.auth.password') }}</label>
-				<Password
-					:validate-initially="validatePasswordInitially"
-					@submit="submit"
-					@update:modelValue="v => credentials.password = v"
-				/>
+                                <Password
+                                        :model-value="credentials.password"
+                                        :validate-initially="validatePasswordInitially"
+                                        @submit="submit"
+                                        @update:modelValue="v => credentials.password = v"
+                                />
 			</div>
 
 			<XButton
@@ -199,8 +200,9 @@ async function submit() {
 
 	try {
 		await authStore.register(toRaw(credentials))
-	} catch (e) {
-		errorMessage.value = e?.message
-	}
+       } catch (e: unknown) {
+               const err = e as {message?: string}
+               errorMessage.value = err.message ?? ''
+       }
 }
 </script>
diff --git a/frontend/src/views/user/RequestPasswordReset.vue b/frontend/src/views/user/RequestPasswordReset.vue
index 1d2b46bf8..e3607b8cd 100644
--- a/frontend/src/views/user/RequestPasswordReset.vue
+++ b/frontend/src/views/user/RequestPasswordReset.vue
@@ -79,9 +79,10 @@ async function requestPasswordReset() {
 	try {
 		await passwordResetService.requestResetPassword(passwordReset.value)
 		isSuccess.value = true
-	} catch (e) {
-		errorMsg.value = e.response.data.message
-	}
+        } catch (e: unknown) {
+                const err = e as {response?: {data?: {message?: string}}}
+                errorMsg.value = err.response?.data?.message ?? ''
+        }
 }
 </script>
 
diff --git a/frontend/src/views/user/settings/ApiTokens.vue b/frontend/src/views/user/settings/ApiTokens.vue
index 70b474c35..2228948f5 100644
--- a/frontend/src/views/user/settings/ApiTokens.vue
+++ b/frontend/src/views/user/settings/ApiTokens.vue
@@ -18,19 +18,19 @@ const service = new ApiTokenService()
 const tokens = ref<IApiToken[]>([])
 const apiDocsUrl = window.API_URL + '/docs'
 const showCreateForm = ref(false)
-const availableRoutes = ref(null)
+const availableRoutes = ref<Record<string, Record<string, string[]>> | null>(null)
 const newToken = ref<IApiToken>(new ApiTokenModel())
 const newTokenExpiry = ref<string | number>(30)
 const newTokenExpiryCustom = ref(new Date())
-const newTokenPermissions = ref({})
-const newTokenPermissionsGroup = ref({})
+const newTokenPermissions = ref<Record<string, Record<string, boolean>>>({})
+const newTokenPermissionsGroup = ref<Record<string, boolean>>({})
 const newTokenTitleValid = ref(true)
 const newTokenPermissionValid = ref(true)
 const apiTokenTitle = ref()
 const tokenCreatedSuccessMessage = ref('')
 
 const showDeleteModal = ref<boolean>(false)
-const tokenToDelete = ref<IApiToken>()
+const tokenToDelete = ref<IApiToken | null>(null)
 
 const {t} = useI18n()
 
@@ -50,7 +50,7 @@ onMounted(async () => {
 	tokens.value = await service.getAll()
 	const allRoutes = await service.getAvailableRoutes()
 
-	const routesAvailable = {}
+        const routesAvailable: Record<string, Record<string, string[]>> = {}
 	const keys = Object.keys(allRoutes)
 	keys.sort((a, b) => (a === 'other' ? 1 : b === 'other' ? -1 : 0))
 	keys.forEach(key => {
@@ -63,8 +63,8 @@ onMounted(async () => {
 })
 
 function resetPermissions() {
-	newTokenPermissions.value = {}
-	Object.entries(availableRoutes.value).forEach(entry => {
+        newTokenPermissions.value = {}
+        Object.entries(availableRoutes.value || {}).forEach(entry => {
 		const [group, routes] = entry
 		newTokenPermissions.value[group] = {}
 		Object.keys(routes).forEach(r => {
@@ -74,13 +74,16 @@ function resetPermissions() {
 }
 
 async function deleteToken() {
-	await service.delete(tokenToDelete.value)
-	showDeleteModal.value = false
-	const index = tokens.value.findIndex(el => el.id === tokenToDelete.value.id)
-	tokenToDelete.value = null
-	if (index === -1) {
-		return
-	}
+        if (!tokenToDelete.value) {
+                return
+        }
+        await service.delete(tokenToDelete.value!)
+        showDeleteModal.value = false
+        const index = tokens.value.findIndex(el => el.id === tokenToDelete.value!.id)
+        tokenToDelete.value = null
+        if (index === -1) {
+                return
+        }
 	tokens.value.splice(index, 1)
 }
 
@@ -127,22 +130,22 @@ async function createToken() {
 	showCreateForm.value = false
 }
 
-function formatPermissionTitle(title: string): string {
-	return title.replaceAll('_', ' ')
+function formatPermissionTitle(title: string | number): string {
+        return String(title).split('_').join(' ')
 }
 
-function selectPermissionGroup(group: string, checked: boolean) {
-	Object.entries(availableRoutes.value[group]).forEach(entry => {
+function selectPermissionGroup(group: string | number, checked: boolean) {
+        Object.entries(availableRoutes.value?.[group] || {}).forEach(entry => {
 		const [key] = entry
 		newTokenPermissions.value[group][key] = checked
 	})
 }
 
-function toggleGroupPermissionsFromChild(group: string, checked: boolean) {
-	if (checked) {
-		// Check if all permissions of that group are checked and check the "select all" checkbox in that case
-		let allChecked = true
-		Object.entries(availableRoutes.value[group]).forEach(entry => {
+function toggleGroupPermissionsFromChild(group: string | number, checked: boolean) {
+        if (checked) {
+                // Check if all permissions of that group are checked and check the "select all" checkbox in that case
+                let allChecked = true
+                Object.entries(availableRoutes.value?.[group] || {}).forEach(entry => {
 			const [key] = entry
 			if (!newTokenPermissions.value[group][key]) {
 				allChecked = false
@@ -368,7 +371,7 @@ function toggleGroupPermissionsFromChild(group: string, checked: boolean) {
 
 			<template #text>
 				<p>
-					{{ $t('user.settings.apiTokens.delete.text1', {token: tokenToDelete.title}) }}<br>
+                                        {{ $t('user.settings.apiTokens.delete.text1', {token: tokenToDelete?.title}) }}<br>
 					{{ $t('user.settings.apiTokens.delete.text2') }}
 				</p>
 			</template>
diff --git a/frontend/src/views/user/settings/Avatar.vue b/frontend/src/views/user/settings/Avatar.vue
index 69d957a91..a1c9ec8d4 100644
--- a/frontend/src/views/user/settings/Avatar.vue
+++ b/frontend/src/views/user/settings/Avatar.vue
@@ -33,7 +33,7 @@
 				<XButton
 					v-if="!isCropAvatar"
 					:loading="avatarService.loading || loading"
-					@click="avatarUploadInput.click()"
+                                        @click="avatarUploadInput?.click()"
 				>
 					{{ $t('user.settings.avatar.uploadAvatar') }}
 				</XButton>
@@ -87,6 +87,7 @@ import {useTitle} from '@/composables/useTitle'
 import {success} from '@/message'
 import {useAuthStore} from '@/stores/auth'
 import Message from '@/components/misc/Message.vue'
+import type { AvatarProvider } from '@/modelTypes/IAvatar'
 
 const {t} = useI18n({useScope: 'global'})
 const authStore = useAuthStore()
@@ -106,11 +107,11 @@ const avatarService = shallowReactive(new AvatarService())
 const loading = ref(false)
 
 
-const avatarProvider = ref('')
+const avatarProvider = ref<AvatarProvider>('default')
 
 async function avatarStatus() {
-	const {avatarProvider: currentProvider} = await avatarService.get({})
-	avatarProvider.value = currentProvider
+        const {avatarProvider: currentProvider} = await avatarService.get(new AvatarModel({}))
+        avatarProvider.value = currentProvider
 }
 
 avatarStatus()
@@ -134,9 +135,11 @@ async function uploadAvatar() {
 		return
 	}
 
-	try {
-		const blob = await new Promise(resolve => canvas.toBlob(blob => resolve(blob)))
-		await avatarService.create(blob)
+        try {
+                const blob = await new Promise<Blob | null>(resolve => canvas.toBlob((b: Blob | null) => resolve(b)))
+                if (blob) {
+                        await avatarService.create(blob)
+                }
 		success({message: t('user.settings.avatar.setSuccess')})
 		authStore.reloadAvatar()
 	} finally {
@@ -145,24 +148,26 @@ async function uploadAvatar() {
 	}
 }
 
-const avatarToCrop = ref()
-const avatarUploadInput = ref()
+const avatarToCrop = ref<string | ArrayBuffer | null>(null)
+const avatarUploadInput = ref<HTMLInputElement | null>(null)
 
 function cropAvatar() {
-	const avatar = avatarUploadInput.value.files
+        const files = avatarUploadInput.value?.files
 
-	if (avatar.length === 0) {
-		return
-	}
+        if (!files || files.length === 0) {
+                return
+        }
 
 	loading.value = true
-	const reader = new FileReader()
-	reader.onload = e => {
-		avatarToCrop.value = e.target.result
-		isCropAvatar.value = true
-	}
+        const reader = new FileReader()
+        reader.onload = e => {
+                const target = e.target as FileReader | null
+                if (!target) return
+                avatarToCrop.value = target.result
+                isCropAvatar.value = true
+        }
 	reader.onloadend = () => loading.value = false
-	reader.readAsDataURL(avatar[0])
+        reader.readAsDataURL(files[0])
 }
 </script>
 
diff --git a/frontend/src/views/user/settings/Caldav.vue b/frontend/src/views/user/settings/Caldav.vue
index 858bb2497..81284698b 100644
--- a/frontend/src/views/user/settings/Caldav.vue
+++ b/frontend/src/views/user/settings/Caldav.vue
@@ -109,6 +109,7 @@ import {success} from '@/message'
 import BaseButton from '@/components/base/BaseButton.vue'
 import Message from '@/components/misc/Message.vue'
 import CaldavTokenService from '@/services/caldavToken'
+import CaldavTokenModel from '@/models/caldavToken'
 import { formatDateShort } from '@/helpers/time/formatDate'
 import type {ICaldavToken} from '@/modelTypes/ICaldavToken'
 import {useConfigStore} from '@/stores/config'
@@ -128,8 +129,10 @@ service.getAll().then((result: ICaldavToken[]) => {
 
 const newToken = ref<ICaldavToken>()
 async function createToken() {
-	newToken.value = await service.create({}) as ICaldavToken
-	tokens.value.push(newToken.value)
+       // The API does not require any payload when creating a token.
+       // Create an empty model instance to satisfy the expected type.
+       newToken.value = await service.create(new CaldavTokenModel({}))
+       tokens.value.push(newToken.value)
 }
 
 async function deleteToken(token: ICaldavToken) {
diff --git a/frontend/src/views/user/settings/General.vue b/frontend/src/views/user/settings/General.vue
index 84cfe529a..3879ef535 100644
--- a/frontend/src/views/user/settings/General.vue
+++ b/frontend/src/views/user/settings/General.vue
@@ -26,7 +26,7 @@
 				v-if="isExternalUser"
 				class="help"
 			>
-				{{ $t('user.settings.general.externalUserNameChange', {provider: authStore.info.authProvider}) }}
+                                {{ $t('user.settings.general.externalUserNameChange', {provider: authStore.info?.authProvider}) }}
 			</p>
 		</div>
 		<div class="field">
@@ -252,7 +252,7 @@ export default {name: 'UserSettingsGeneral'}
 </script>
 
 <script setup lang="ts">
-import {computed, watch, ref} from 'vue'
+import {computed, watch, ref, type Ref} from 'vue'
 import {useI18n} from 'vue-i18n'
 
 import {PrefixMode} from '@/modules/parseTaskText'
@@ -271,6 +271,8 @@ import {useAuthStore} from '@/stores/auth'
 import type {IUserSettings} from '@/modelTypes/IUserSettings'
 import {isSavedFilter} from '@/services/savedFilter'
 import {DEFAULT_PROJECT_VIEW_SETTINGS} from '@/modelTypes/IProjectView'
+import type {IProject} from '@/modelTypes/IProject'
+import ProjectModel from '@/models/project'
 import {PRIORITIES} from '@/constants/priorities'
 
 const {t} = useI18n({useScope: 'global'})
@@ -309,9 +311,9 @@ function useAvailableTimezones(settingsRef: Ref<IUserSettings>) {
 		.then(r => {
 			if (r.data) {
 				// Transform timezones into objects with value/label pairs
-				availableTimezones.value = r.data
-					.sort((a, b) => a.localeCompare(b))
-					.map((tz: string) => ({
+                                availableTimezones.value = r.data
+                                        .sort((a: string, b: string) => a.localeCompare(b))
+                                        .map((tz: string) => ({
 						value: tz,
 						label: tz.replace(/_/g, ' '),
 					}))
@@ -364,12 +366,12 @@ const {
 
 const id = ref(createRandomID())
 const availableLanguageOptions = ref(
-	Object.entries(SUPPORTED_LOCALES)
-		.map(l => ({code: l[0], title: l[1]}))
-		.sort((a, b) => a.title.localeCompare(b.title)),
+        Object.entries(SUPPORTED_LOCALES)
+                .map(l => ({code: l[0], title: l[1]}))
+                .sort((a: {code: string; title: string}, b: {code: string; title: string}) => a.title.localeCompare(b.title)),
 )
 
-const isExternalUser = computed(() => !authStore.info.isLocalUser)
+const isExternalUser = computed(() => !authStore.info?.isLocalUser)
 
 watch(
 	() => authStore.settings,
@@ -384,25 +386,30 @@ watch(
 )
 
 const projectStore = useProjectStore()
-const defaultProject = computed({
-	get: () => projectStore.projects[settings.value.defaultProjectId],
-	set(l) {
-		settings.value.defaultProjectId = l ? l.id : DEFAULT_PROJECT_ID
-	},
+const defaultProject = computed<IProject>({
+        get: () => settings.value.defaultProjectId !== undefined
+                ? (projectStore.projects[settings.value.defaultProjectId] as IProject) ?? new ProjectModel()
+                : new ProjectModel(),
+        set(l: IProject) {
+                settings.value.defaultProjectId = l ? l.id : DEFAULT_PROJECT_ID
+        },
 })
-const filterUsedInOverview = computed({
-	get: () => projectStore.projects[settings.value.frontendSettings.filterIdUsedOnOverview],
-	set(l) {
-		settings.value.frontendSettings.filterIdUsedOnOverview = l ? l.id : null
-	},
+const filterUsedInOverview = computed<IProject>({
+        get: () => settings.value.frontendSettings.filterIdUsedOnOverview !== null
+                ? (projectStore.projects[settings.value.frontendSettings.filterIdUsedOnOverview] as IProject) ?? new ProjectModel()
+                : new ProjectModel(),
+        set(l: IProject) {
+                settings.value.frontendSettings.filterIdUsedOnOverview = l ? l.id : null
+        },
 })
-const hasFilters = computed(() => typeof projectStore.projectsArray.find(p => isSavedFilter(p)) !== 'undefined')
+const hasFilters = computed(() => typeof projectStore.projectsArray.find(p => isSavedFilter(p as IProject)) !== 'undefined')
 const loading = computed(() => authStore.isLoadingGeneralSettings)
 
 async function updateSettings() {
-	await authStore.saveUserSettings({
-		settings: {...settings.value},
-	})
+        await authStore.saveUserSettings({
+                settings: {...settings.value},
+                showMessage: true,
+        })
 }
 </script>
 
diff --git a/frontend/src/views/user/settings/TOTP.vue b/frontend/src/views/user/settings/TOTP.vue
index f10049c98..ad69465ad 100644
--- a/frontend/src/views/user/settings/TOTP.vue
+++ b/frontend/src/views/user/settings/TOTP.vue
@@ -135,7 +135,7 @@ async function totpStatus() {
 		return
 	}
 	try {
-		totp.value = await totpService.get({})
+        totp.value = await totpService.get(new TotpModel())
 		totpSetQrCode()
 	} catch(e: unknown) {
 		// Error code 1016 means totp is not enabled, we don't need an error in that case.
diff --git a/frontend/tsconfig.app.json b/frontend/tsconfig.app.json
index 8ef3f524f..c05a1cc2f 100644
--- a/frontend/tsconfig.app.json
+++ b/frontend/tsconfig.app.json
@@ -20,7 +20,8 @@
     "strictNullChecks": true,
     
     "paths": {
-      "@/*": ["./src/*"]
+      "@/*": ["./src/*"],
+      "vite-plugin-sentry/client": ["./node_modules/vite-plugin-sentry/client.d.ts"]
     },
     "types": [
       // https://github.com/ikenfin/vite-plugin-sentry#typescript
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index df08e5f1b..9d2201fce 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -1,5 +1,5 @@
 /// <reference types="vitest" />
-import {defineConfig, type PluginOption, loadEnv} from 'vite'
+import {defineConfig, type PluginOption, loadEnv, type ImportMetaEnv} from 'vite'
 import {configDefaults} from 'vitest/config'
 import vue from '@vitejs/plugin-vue'
 import {URL, fileURLToPath} from 'node:url'