sendEmail caught transport failures internally and resolved to false or
undefined, so every caller's .catch() was dead code and send failures were
silently suppressed. Password recovery in particular reported "email sent
successfully" while the user received nothing.
sendEmail now throws an AppError carrying the underlying cause, and returns
Promise<string> instead of Promise<string | false | undefined>.
Call sites updated for the new contract:
- UserService.registerUser: the existing .catch() now actually fires
- UserService.requestRecovery: the failure reaches the client instead of a
misleading success response
- InviteService and the test-email endpoint: keep their user-facing messages
and attach the SMTP cause
- EmailProvider: catches and returns false, because NotificationsService fans
providers out through Promise.all and a rejection there would abort the
other channels' alerts
Closes#3757
egeoztass
Alex Holliday