"change [variable] by (1)" block does not result in NaN when manipulating strings

[thisandagain]

Expected Behavior

Executing the "change [variable] by (1)" block on a variable that is currently set to a string should result in NaN

Actual Behavior

The variable is set to 0

Steps to Reproduce

Reference

https://scratch.mit.edu/projects/275276918
https://llk.github.io/scratch-gui/develop/#275276918

Major HT to Scratcher hahasamian for identifying this issue!

/cc @kchadha @ktbee

[apple502j]

Wait, compat wiki mentions this.
https://github.com/LLK/scratch-vm/wiki/Compatibility#consistent-type-coercion-when-modifying-variables
Should it be fixed or kept? @thisandagain

[thisandagain]

@apple502j Yeah. This was one of the very first things we decided to change. I'd like to discuss this.