Hey Agnes,
I was able to get the study to save by assigning attaching the psychoJS instance to the window object, which in turn makes it globally available. There are other ways of achieving the same result in JS (e.g., using a Singleton), but none less complicated. I also added a ‘util’ module to host saveTrialData() for sharing across scenes.
The one resources related error at the very beginning is a PsychoJS bug I’m hoping to have fixed in the next few days.
Commenting out the taskEndScene.js#L100 psychoJS.quit() call seems to have made the rest of errors go away. That allowed for the data to be saved as expected I believe, but I could be missing something 
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