Thank you for looking that up. Throwing (rather than returning exceptions) is definitely a good idea, however, it won't solve this particular problem or create a more stable customization interface.

The default implementation of the global error handler does just that, throw an exception, politely, with croak no less. The problem I was struggling with isn't how to pass the exception (return value, throwing), but rather (a) how best to work with the way this particular module chose to support customization of the throwing behavior (b) how to support customization of hooks (error handlers or others) without creating the issues presented by a global handler.

Best, beth