Improve syntax error message for `case 1:` statement

[sobolevn]

Feature or enhancement

Right now just case without match produces:

>>> case 1:
  File "<python-input-0>", line 1
    case 1:
         ^
SyntaxError: invalid syntax

I propose to add a better hint:

>>> case 1:
  File "<python-input-0>", line 1
    case 1:
         ^
SyntaxError: case statement must be inside match statement

I have a PR ready.
I also have several other ideas about better error messages for match and case :)

Linked PRs

• gh-138857: Improve error message for case outside of match #138858

[raman118]

working on this now

[StanFromIreland]

@raman118

In the future please read issues carefully, in this case the author noted:

I have a PR ready.