This point came home recently in doing a little macro to load a directory of GeoJSON documents into QGIS.
You need to load the Python console to get the proper environment, and you can't just say logger.debug() to get a trace.
This is because QGIS runs in the Qt event loop.
Big cluebat: QGIS (qualitatively, and for the regular pythonista) is like doing everything via asyncio.
Ah, so: no wonder it's such a challenge.