Power BI Service refresh error when using custom M functions for REST API calls + on-prem gateway

I will if all tests fail.  atm though this page explained why the issue exists in the first place:  https://learn.microsoft.com/en-us/power-query/dataprivacyfirewall

And thanks to other users saying that there can be no reference to external local queries from within the query where you call the REST API if you also combine data from other sources in that same query, I was able to get the Service to finally refresh without errors.  

HOWEVER, that is not say that PQ could not be improved so that the naive user wouldn't have to resort to such ugly code gymnastics while at the same time still preserving data privacy.

Initial testing succeeded.  I was able to bring in a data subset into Service and have it refresh no problem. But honestly, what a royal pain in the ass it was to get to this point.  I wish esoteric stuff like this would be advertised front and center when you hit the PQ documentation, because quite frankly, anyone starting out with Power BI will never imagine there is such a thing as a data privacy firewall.  We all just start plugging away as fast as we can with DAX and a little M, then more M but who has the time to dig deep into the documentation, especially the advanced topics?