fix(export): treat a missing export meta row as no export in the status

GetUserDataExportStatus propagated the raw LoadFileMetaByID error when the
meta row was gone, so /user/export could 500. The download path already
maps that case to ErrUserDataExportDoesNotExist (404); make status
consistent by returning nil (no export), matching the documented contract.

pkg/models/export.go

@@ -438,6 +438,11 @@ func GetUserDataExportStatus(u *user.User) (*UserExportStatus, error) {
 
 	exportFile := &files.File{ID: u.ExportFileID}
 	if err := exportFile.LoadFileMetaByID(); err != nil {
+		// A missing meta row means there is no export — mirror the download path
+		// (404 there) instead of surfacing a 500.
+		if files.IsErrFileDoesNotExist(err) {
+			return nil, nil
+		}
 		return nil, err
 	}
 

pkg/models/export_test.go

@@ -0,0 +1,53 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"testing"
+
+	"code.vikunja.io/api/pkg/db"
+	"code.vikunja.io/api/pkg/user"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetUserDataExportStatus(t *testing.T) {
+	t.Run("no export", func(t *testing.T) {
+		db.LoadAndAssertFixtures(t)
+		status, err := GetUserDataExportStatus(&user.User{ID: 15})
+		require.NoError(t, err)
+		assert.Nil(t, status)
+	})
+
+	t.Run("with export", func(t *testing.T) {
+		db.LoadAndAssertFixtures(t)
+		status, err := GetUserDataExportStatus(&user.User{ID: 1, ExportFileID: 1})
+		require.NoError(t, err)
+		require.NotNil(t, status)
+		assert.Equal(t, int64(1), status.ID)
+	})
+
+	t.Run("export points at a missing file", func(t *testing.T) {
+		db.LoadAndAssertFixtures(t)
+		// A dangling ExportFileID must read as "no export" rather than erroring,
+		// matching the download path which 404s the same case.
+		status, err := GetUserDataExportStatus(&user.User{ID: 15, ExportFileID: 9999})
+		require.NoError(t, err)
+		assert.Nil(t, status)
+	})
+}