Regression at least from Version 5.5.2f1 (acf780a2145d) Fri, 17 Feb 2017 15:35:32 GMT Branch: 5.5/release

Repro steps:

1. Create a new project (or open attached one)
2. Add any script in it
3. Go to Building settings
4. Select the platform that is not your current one ==> Do not switch to that platform!
5.Press "Build and Run"
==>
Editor crashes on the phase "Building Resource folder"

Please , see attached movie for details
Note: Not reproducible if user explicitly switches to another platform and builds