Make pre-increment/decrement show as error/warning?

[esotericpig]

Coming from C/C++, I just intuitively did this:

var i := 0

++i

print("i is ",i) #=> 0

Currently, this doesn't report as a warning/error in the editor (unlike post-increment/decrement).

[theraot]

Currently, it is an standalone expression warning.

[esotericpig]

Ah okay, I see that now. Thank you. Maybe could be an error then? i++ actually causes an error.

[Calinou]

Thanks for the proposal! Consolidating in #8829.