credfeto-error-handling

name	credfeto-error-handling
description	Handle and propagate errors explicitly — catch only what can be meaningfully handled, preserve root causes when wrapping, and sanitise errors surfaced to external callers. Use whenever writing or reviewing error handling, exception handling, or error propagation code in any language.

Error Handling

General Principles (MANDATORY)

• All errors must be handled explicitly — never swallow exceptions or silently ignore error states.
• Unhandled errors must not be allowed to crash a service or leave the system in an inconsistent state.

Catching Errors

• Only catch errors you can meaningfully handle at that point — do not catch broadly just to suppress errors.
• If an error cannot be handled locally, let it propagate to a level that can handle it, or wrap it in a more contextual error and rethrow.
• Never catch an error, log it, and then rethrow it — this leads to duplicate log entries; either handle it or rethrow it.

Propagation

• Errors should carry enough context to be diagnosable — include relevant identifiers, inputs, or state when wrapping errors.
• Do not lose the original cause when wrapping errors; always chain or preserve the root cause.

Surfacing

• Errors that are exposed to external callers (e.g. API responses) must be sanitised — do not leak internal implementation details, stack traces, or sensitive data in error responses.
• Use appropriate error codes or status indicators for the protocol in use (e.g. HTTP status codes for REST APIs).