Trouble with CORS when hosting server and client in different places

Hey there! I’m trying to run a basic multiplayer app built with Phaser. I have the server hosted on Glitch, and the client hosted on itch. I almost have everything running, with one issue: when I access the game on itch, I get a bunch of CORS errors. I’ve tried code like this to fix it:

But I still get errors. The page where the client is hosted is here: phaser multiplayer test by slimefriend

Am I configuring the cors headers wrong here? Or is there some other gotcha I’m missing? I’m brand new to this so I’m having some trouble.

Thanks for your help,

Taylor Anderson