Raised when an app exits with a non-zero exit code.

Raised by the app decorator instead of calling sys.exit, so callers can catch a normal exception and e.g. call sys.exit(exit_code) in a runner.

Structured metadata about the cause of an app exit error.

Always includes error_type. May include additional fields like block_type for specific error types (e.g., UnsupportedAwaitUserBlockError).