Yarn - nameTag error "Cannot read properties of undefined (reading 'vertices')"

Hi there, this is my first time using this forum so apologies in advance if I miss anything.
In my game, I’ve followed this tutorial for two games now, and it’s served me very well up until this point!

The issue I’m coming across is that once the nameTag has to change animations, the game crashes. I genuinely don’t know why this is happening, and the issue disappears if I change the nameTag to a specific animation, or I set it to << nameTag none >>, but that’s not very helpful, seeing as I don’t want everybody in my game to be a librarian.

As you can see, the only thing I’ve changed here is the title of the nameTag but then these two different things happen depending on which one I call. With one, I get a huge error message.

The error itself says “Cannot read properties of undefined (reading ‘vertices’)” but despite looking up what that means, I still have no idea why it’s happening.

I’ve found that if I don’t have to switch characters, this doesn’t happen, but say I have a dialogue sequence that goes

Character A: hi
Character B: hi!
Character A: ok bye

The second time that the nameTag for Character A is called, this error happens… so it’s not an issue of being able to retrieve the nameTag, as the program has already done so before. I guess that’s why I’m so confused.

This isn’t just for this scene, either, it’s happening throughout the game if multiple characters are called upon!
Thanks in advance, let me know if you need any more context!