My datapack functions are broken...

So, my tick function and many other functions suddenly stopped working. Whenever I tried to run them, I got an error saying something like "Unsupported Operation" with the text java.lang.UnsupportedOperationException when I hovered over it. I didn't make any changes to the files, and it worked perfectly fine when I tested it yesterday. I thought it had something to do with updating to the latest snapshot (05a) but when I went back to the previous one it had the same errors. There are no errors marked in VS Code. Any idea why this is happening?? :((