Just needs a simple check.
This error has been happening since a while ago, and I don’t think a fix was ever found. I know it only happens on Mac (well, used to) and only happens when using typing in the chat bar.
How do you log errors like that?
[quote]
Just needs a simple check. [/quote]
You can always file a pull request to fix this in the core script 
However I actually think this is something that needs fixing in UserInputService. I was assigned to fix the bug as referenced here on Anaminus’ bug tracker but I could not reproduce it.
Do you have any reproduction steps?
I have a hunch it has something to do with alt codes, but I don’t think I was in the game when this got logged to my Trello.
Also it appears on line 1499 as well.