Should throw exception when a called function does not exist.

[cgillum]

Today if a user calls DurableOrchestrationClient.StartNewAsync or DurableOrchestrationContext.CallFunctionAsync and specifies a function name which doesn't exist, the call fails silently.

Instead, these methods should throw an exception that can be handled/logged by user code.

[cgillum]

This is fixed in the latest release. If you try to call a function that doesn't exist, an exception will be thrown and the message will include all the active function names, making it easier to figure out what went wrong.