NPEs are handled differently between instructions

felixtsu · June 21, 2020, 4:05am

Looks like NPEs are handled differently between instructions, some fail silently while some immediately raise a programming error, is it possible a consistent Fail Fast, Fail Early behavior is kept across all instructions?

The following program runs, but sprite cannot be moved with buttons.

The following program eagerly raise an NPE.

richard · June 22, 2020, 4:19pm

Could you file this on github?

felixtsu · June 23, 2020, 4:12am

Yup, here it is.

I’m suggesting the change for it gives the students an immediate feedback on ‘Variables need initialization before usage’ violation, which is mentioned in 2016 MA Digital Literacy and Computer Science Curriculum.