Processing example quits without error message

[PaulStoffregen]

While helping Alysia convert files for the Space Whale project, the Processing code would show the window briefly, then exit without any indication why it failed. Turned out it couldn't write the file, probably due to a permissions issue. But no error message prints, which makes troubleshooting much harder than it should be.

Also might have a compatibility issue with setting the window size on Processing version 3. Testing needed.