Right. Looks like that there's a conflict with the "Source code protection" feature in your case. It was turned on by default in recent versions of the tool. There are two options for this:
1. Turn off the feature. It's found under Project Settings -> Essentials tab.
2. On the same tab, you can turn on the option to create test builds. Once your create a build, you can run the game as normal and then press F12 to open the dev console. If there is an error, a plugin broke. Usually, it's due to trying to pull its name dynamically (via `document.currentScript.src`) so it can pull the settings. If you have time, I can help out via Discord (same username and avatar as here).