Locating origin of "SyntaxError: Unexpected end of input"

Hello all!

I’m experiencing some issues when trying to log in to my app as a user.
It looks like this might be related to the “Canvas” plugin I’m using.

Basically, the login succeeds, the redirection to the “index” page takes place (correctly), but then the parameters in the address bar change to something like “?m=signup&resume=1623013529004x595103567536508700” and I can’t understand where that comes from.
Then, the index page reloads and keeps looping between those two states forever.

Log files log the actions in the workflow, but not what triggers the infinite loop.

Any idea how I can debug this issue?