Handle errors

Classify before rendering

• Validation and domain rejection are expected outcomes near the action.
• HTTP timeout, abort, offline, and non-success status belong to the request owner.
• Route resolve failure belongs to transition policy.
• Unexpected exceptions belong to $exceptionHandler and diagnostics.

Do not convert every rejection to [], null, or false. That destroys information and commonly renders an empty success state after a real failure.

Wrap low-level errors with the operation name while retaining the original cause. The UI should receive a stable category and recovery action, not a stack trace or server payload. Logs may include release, route, operation, and correlation identifiers but must exclude credentials and private data.

A repository may retry a safe idempotent read. A component should own the retry button. Global interceptors should refresh credentials or normalize protocol behavior, not retry every request indiscriminately.

Unexpected exceptions should reach the $exceptionHandler reference. Test that expected failures remain recoverable and unexpected exceptions are reported.