Firefox throwing "IndexSizeError: Index or size is negative or greater than the allowed amount" error.

[ahmerrkhanzz]

I have set the limit of text in the editor and when i "ctrl+z" the exceeded text it gives me "IndexSizeError: Index or size is negative or greater than the allowed amount" error. Everything is working perfectly in chrome. It happens only inn Firefox.

[thiazzz]

I get the same in Firefox IndexSizeError: Index or size is negative or greater than the allowed amount