Huma's handler-error path wraps raw errors as NewErrorWithContext(ctx,
500, "unexpected error occurred", err), and since the humaecho5 adapter
writes Huma's response directly it bypasses Vikunja's
CreateHTTPErrorHandler — which returns a generic 500 with no detail for
non-domain errors. The huma.NewError override then copied err.Error()
(raw DB/driver messages, SQL, table/column names) into the problem+json
errors[], a regression vs v1.
Override huma.NewErrorWithContext to drop errs for status >= 500, log
the real cause server-side, and return a generic body. 4xx detail
(validation errors, domain messages) is unaffected.