SecurityError: The operation is insecure. websocket-debugger-client.js:15
Tried on Ubuntu 18.04 and Windows 10. Get the same result.
I know this problem has been already discussed on GitHub and been closed saying it Firefox internal problem they need to fix it, BUT! Firefox got 2 or 3 updates since, clearly not fixed whatever it is and all similar online editors does work in Firefox except GDevelop. It maybe internal to Firefox but competitors got their editors working so.....
Regardless the advantages of Chrome, I do use Firefox all day as my main browser for all tasks and I find my self a lot jumping in to GD online editor to try something then realize the preview doesn't work so then I need to fire up Chrome and start all over again.
It may be considered not a big problem but when I realize it AFTER messing in the editor 10 minutes or more, it can be an unpleasant experience. I use the online editor a lot to try staff quickly without I need to setup a new project on my PC.