I created a GUI for an entity that I created. When I tried to test it using the test client, this came up.
See here: https://pastebin.com/afu6kFs9
I am not sure how to fix the errors, as I did not type that code. That code was auto generated by MCreator. I also cannot fix it as I don't know Java. The specific mod element that is causing a problem is the Piglin Villager GUI.