Special error message for pre- or postfix operators immediately next to other operators

[byorgey]

Disco> Disco> 1/-1
1:2:
  |
1 | 1/-1
  |  ^
unexpected '/'
expecting digit, end of input, expression, operator, or type annotation
Disco> 1/ -1
-1

Can we fix this? /- is not a valid operator so it would be nice if the parser could figure this out.

[byorgey]

Ah, well, if we implement #136, then /- could be a valid operator... I think we shouldn't fix this. But I'm leaving this ticket open and repurposing it to see if we can generate a special error message when this situation occurs.

[byorgey]

Note a similar kind of thing can happen with postfix operators right next to other operators:

Disco> 10! * 11!/5!
1:9:
  |
1 | 10! * 11!/5!
  |         ^
unexpected '!'
expecting digit, end of input, expression, operator, or type annotation

[byorgey]

#101 could conceivably help with this.