Diaeresis marks on international keyboards cause an error. A warning message might be more appropriate.

Describe the bug

I was working with a student today who primarily uses an international keyboard. From what I was able to discern her keyboard was mapping the quotation mark character to the Unicode diaeresis (¨) character. It took a good five minutes to figure out what was happening. From a distance, and on lower resolution laptops, diaeresis and quotation marks look incredibly similar (¨ vs "). It would be great if there was a way to detect when this was happening and warn users. I am unsure of what particular international keyboard settings were being used but I could find out if it would be helpful.

To Reproduce

Here is an example of the behavior.
https://popcode.org/?snapshot=7eb205a0-f042-4084-80b5-5b2397778c08

Expected behavior

It would be amazing if we could detect when this occurs and present users with a warning, perhaps with instructions on how to change their keyboard mapping. Simply grepping the student source code would probably be sufficient. Alternatively, highlighting diaeresis marks and similar characters could make the problem easier to spot.

Screenshots

• OS: [e.g. iOS]

Chrome book

• Browser [e.g. chrome, safari]

Google Chrome

• Version [e.g. 22]

Version unknown

Additional context

Happy to discuss further if it would help. I would love to teach the students about the process of submitting a bug report / issue. ❤️
Thanks for you help! Popcode is great project!

まず、Chromebook 上の Chrome で国際キーボードを使い、リンクされたスナップショットで問題を再現します。次に、学生のソースコードがどのように検査またはレンダリングされるかを追跡し、ユーザーがキーボードマッピングの問題を特定できるよう、ダイエリシス文字に対する明確な警告またはハイライト表示を完了条件として定義します。