OptionalerrorMessage: stringHandles the given input. This may only be called if canHandle did not reject. When unconditionally calling both in sequence, consider handleSafe instead.
A promise resolving when handling is finished.
Helper function that first runs canHandle followed by handle. Throws the error of canHandle if the data cannot be handled, or returns the result of handle otherwise.
Input data that will be handled if it can be handled.
A promise resolving if the input can be handled, rejecting with an Error if not.
Handler that does not support any input and will always throw an error.