"TypeError: this is undefined" only on psychopy version 2020.2.3

URL of experiment:

Description of the problem:

The experiment works fine locally and offline through experiment runner.

I have been told to upgrade from 2020.1.3 to 2020.2.3 in order to fix some other issues I’ve been having. However, twice now after upgrading version and uploading experiment to pavlovia, I get the below error immediately as the experiment is started (piloted).

Is this a bug? Or does it mean a variable named “this” is undefined? What I don’t understand is how the experiment managed to get past this beginning bit when using 2020.1.3.

For some extra context, this was the issue I was having with the older version:

Any help would be greatly appreciated, thanks.

EDIT: These are the errors shown using the browser console:

What was probably happening was that the Python associated with the $ in your components was not being translated into JS, so it ran fine. It probably is a variable called this that is not being declared somewhere

What happens on line 527 of your script? It’s probably sending a dud value up the stack

Hi Oli, thanks for your reply.

I have just managed to fix the problem, it related to how java was reading the conditions file.
Essentially, there was a image file name variable defined in the spreadsheet that sometimes had blank rows, which caused everything to fail.
I replaced the blank rows with a 1x1 pixel image that I set to 0 size, which seems to have fixed the problem.

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Thanks!

H

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