Mal-formed user patterns prevent app from loading

[matthewkaney]

In the current Strudel, if you try to duplicate the "current" pattern from a default state where no pattern is selected, then it creates a duplicate pattern where the code field is missing. This immediately crashes the app because the pattern tab tries to access the code in order to search for metadata and passing undefined into a regex is a Javascript error.

Reproduction Steps

Do this in a private browsing window or some other context with separate local storage!

• Open strudel.cc
• Navigate to the user patterns tab
  • On first-run, there won't be a selected pattern
• Click on duplicate
• The interface should crash and will crash every time you return to the app

If this happens and you need to recover:

• In the app, open the browser's Javascript console
• Run localStorage.clear() which will delete all of your saved patterns and settings