Editor doesn't support simultaneous `delete/insert` events

[knpwrs]

1. Type something in the first editor.
2. Select everything in the second editor and type over the text.
3. The first editor will have both sentences typed out, the second editor will only have the second.

[sunny-b]

Thanks for this, that's definitely an oversight on our part.

The way we have it set up right now is we detect whenever CodeMirror sends an "insert" or "delete" event. This is an edge case where it's technically an insert and delete at the same time. The solution will probably involve detecting this type of operation when an "insert" event occurs or disabling it entirely. At least for now. Less user friendly but maintains consistency.

[sunny-b]

Fixed