Error Handling Strategy

Design an error handling strategy for {{app_or_feature}} in {{stack}}. Recommend how to distinguish recoverable from fatal errors, where to catch versus let errors propagate, consistent error types and messages, what to log versus show the user, retries and fallbacks where appropriate, graceful degradation, and how to avoid both swallowing errors silently and crashing on every hiccup. Make failures predictable and debuggable, and note the most common error-handling anti-pattern to avoid.