Can't Save Custom Symbol Display

Question

Hey all, I created some custom symbols that I can add to a display and are working how I want. Has anyone had trouble with saving custom symbols like this?

Here's an example.

However, when I save the display and try to reopen it, the page doesn't load.

And there are quite a lot of errors like this in the console

Jack Morse · Accepted Answer

The issue was that I had an extra custom symbol in my folder. Must've been a leftover from someone else, or I added and forgot about it myself. Make sure that you don't have any extra, partial symbols in your folder structure and you should be good.