Running experiment online: TypeError: this._renderer.gl is undefined

As said, I am simply trying to run my experiment online. It works perfectly on the Builder and on the Coder. But when I run the experiment online (https://pavlovia.org/run/marie.cote/morphologie/html/), I get different errors depending on the navigator I’m using.

With Chrome and Opera, I get:
Unfortunately we encountered an error:
** TypeError: Cannot read property ‘readPixels’ of undefined*
Try to run the experiment again. If the error persists, contact the experimenter.

With Internet Explorer and Microsoft Edge, I simply get a blank page.

With Safari, the page is not loading either and it says:
Safari can’t open the page.
Safari can’t open the page “https://pavlovia/run/marie.cote/morphologie.html”. The error is “”(kCFErrorDomainWinSock:10054) Please choose Safari > Report Bugs to Apple, note the error number, and describe what you did before you saw this message.

It’s with Firefox that I get the TypeError: this._renderer.gl is undefined error.

Here’s a link to my project’s files, I made it public: https://gitlab.pavlovia.org/marie.cote/morphologie. You can run my file Epreuves_morpho.psyexp on PsychoPy to see what’s supposed to appear when I run my experiment online.

I thank you in advance.

P.S. You’re talking about seeing “how the error is generated”… There’s a way to see that? 'cause a big part of what makes me unable to debug my code myself is the fact that the error code isn’t pointing towards a specific part of my project’s code…

P.S.2 I can’t write JavaScript so I can’t test this solution, but is this answer applicable to my problem? ReferenceError when running study online I have code components that are only written in Python… Should I ask someone to translate them into JavaScript for me and put the JavaScript code in my code components, using the “both” option?