Return value when problem(value) finds nothing; otherwise throw a
MudabValidationError with the message Invalid <name>: <reason>.
A client method that returns a promise calls it inside its async body, so a
rejected input rejects the promise, and no request is sent.
Return
valuewhenproblem(value)finds nothing; otherwise throw a MudabValidationError with the messageInvalid <name>: <reason>. A client method that returns a promise calls it inside its async body, so a rejected input rejects the promise, and no request is sent.