The pre-ship checklist

I'm about to share this with real people. Here is the code: <paste>

Go through it as if you were the first stranger to use it. Report:
- Anything that breaks on a phone.
- Anything that breaks with slow or no network.
- Anything that breaks if a user types something unexpected, or nothing.
- Anything that leaks a key, a path, or an internal error message.
- Anything that would lose someone's work — an unsaved form, a refresh.

Rank the findings by how embarrassing they'd be, worst first.