I have the following setup in a REST API Method:

In the Debugger it wants me to open the module in Google Chrome, but this module is meant to run in the background, it has no screens. There's an integration with a service later on down the line that sends a notification email, and it's only supposed to send one email, but it's sending the same email twice, and I think this REST API Method is the culprit, but without visibility into each step it's very difficult to know where the error is.

It's an exposed API and I can see in service center that it's only receiving one request with one record ID, and the end result is meant to be one notification email, but it's sending two. 

I have full logging turned on in service center, but that only tells me the incoming request. It calls a dependent service action, and I can't seem to figure out how to get visibility into this step.