WindSoilder d2f513da36
make better error message for not operator (#10507)
Fixes: #10476

After the change, the error message will be something like this:
```nushell
❯ not null
Error: nu:🐚:type_mismatch

  × Type mismatch.
   ╭─[entry #11:1:1]
 1 │ not null
   ·     ──┬─
   ·       ╰── expected bool, found nothing
   ╰────
```
2023-09-26 14:53:59 +02:00
..