<INVALID OREF> with InvokeMethod when params don't match WebClient method signature

I have a Business Operation calling a SOAP WebClient method via InvokeMethod, passing several individual parameters. The call returned $$$OK with no SoapFault, but the output object came back undefined, causing a downstream error when I tried to use it. Turns out the generated WebClient method had been refactored to accept a single request object instead of individual parameters, so my call no longer matched the signature. My question: is this expected — InvokeMethod failing silently (no SoapFault, no error status) when parameters don't match the target method's signature? Is there a way to validate this beforehand instead of only discovering it via a downstream ?