Changed EncrypterInterface property to nullable and added proper error
handling for cases where encryption key is not available.
Changes:
- Config controller: nullable encrypter property, try/catch around encryption
- Email_lib: check encryption before using encrypter
- Return meaningful error messages when encryption fails
- Log warnings when passwords saved without encryption
Users will now see clear error messages instead of unhandled exceptions
when encryption key cannot be initialized.
GitHub-Issue: #4554