Lookup component fails flow when no control message is received

[nrichardson99]

When you have a flow with a lookup component and there is no message (not even a control) that is received by the component the code will throw a misconfigured exception. The message is actually a warning type of message 'The flow completed without the lookup datasource being populated. Please make sure that the lookup datasource is sending a control message'
Should this not fail the flow or should we handle no control message received and allow it because it is a valid scenario.

To re-create. Create a flow with a content router before a lookup that has a failure condition thus not sending any message to the lookup. The error is captured in the flowCompleted method in Lookup.java.
Also could recreate similarly through an embed flow where the router sending nothing is in the calling flow and the lookup is in the embedded flow.