"rot:" without "copy:" causes editor crash

[angilbert]

Describe the bug
The editor crashes with an Uncaught TypeError if a "rot:" is used without "copy:"

Reproduction Steps

1. Load: https://puzzlescriptnext.polyomino.com/editor.html
2. Open the browser console
3. Select Example project Tapaban
4. Edit line 159 and remove the copy: (leaving just the rot: section)

What did you expect would happen?
No crash

OS & Browser version, desktop/mobile
MAC/Chrome/Desktop
Applies to both dev and stable release

Screenshots, example projects, other relevant issues, etc.

[david-pfx]

Thanks! It'll be another case where faulty code triggers a crash in the parser before it gets handled properly.

Will fix.