Update Orchestration Ouput Return error

[nytian]

Fix issue #428

If the orchestrator output includes any type that cannot be serialized into JSON, it will trigger a non-deterministic error. This occurs because the orchestration state must be serialized before it is sent to the durable extension. If there is a serialization issue, the extension cannot replay correctly from this corrupted state, thus treating the situation as non-deterministic. The fix in this PR is to verify whether the orchestration output is serializable. If it is not, an exception will be thrown to indicate that this type of return is not accepted in durable Python.

Noting E2E test,

Orchestrator return includes a exception object.

Former return:

Return with changes in this PR:

[nytian]

I didn't add a test because the wrong error is returned from the durable extension level, not durable python repo. So I am not sure how to do a proper unit test. But I did the E2E test, and the error message is correct.

[davidmrdavid]

Approved conditional on the self.output if statement checking specifically for None.

Thanks so much for fixing this!