Avoid raising bare Exception

[zaicruvoir1rominet]

Summary

Before tackling issue #457, there are some bare Exceptions thrown from within the code.

Here is the logic for changes in Exceptions:

• use ValueError when issue caused by user input
• use CSTValidationError & TypeError when issue occurs during the CST validation process
• use ParserSyntaxError when issue occurs during the parsing process
• use CSTLogicError to replace all Exception which contained "Logic error" in the cause message
• remove Exception catch+re-raise when not needed

I'm all for changes if some Exceptions changes are not OK,
In particular, there are some ParserSyntaxError which may not be meaningful - with raw_line=0, raw_column=0 params

Test Plan

Keep the current test plan.

[codecov]

Codecov Report

Attention: Patch coverage is 25.49020% with 114 lines in your changes missing coverage. Please review.

Project coverage is 91.29%. Comparing base (8b97600) to head (eb3f2a6).
Report is 9 commits behind head on main.

Files	Patch %	Lines
libcst/matchers/_matcher_base.py	9.52%	19 Missing ⚠️
libcst/_parser/conversions/expression.py	18.18%	9 Missing ⚠️
libcst/_parser/conversions/statement.py	18.18%	9 Missing ⚠️
...bcst/codemod/commands/convert_format_to_fstring.py	20.00%	8 Missing ⚠️
libcst/_parser/parso/python/tokenize.py	12.50%	7 Missing ⚠️
libcst/_parser/conversions/params.py	14.28%	6 Missing ⚠️
libcst/codegen/gen_matcher_classes.py	16.66%	5 Missing ⚠️
libcst/helpers/_template.py	0.00%	5 Missing ⚠️
libcst/_nodes/base.py	20.00%	4 Missing ⚠️
libcst/_parser/grammar.py	0.00%	4 Missing ⚠️
... and 19 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1168      +/-   ##
==========================================
+ Coverage   91.26%   91.29%   +0.03%     
==========================================
  Files         261      262       +1     
  Lines       26877    26899      +22     
==========================================
+ Hits        24529    24558      +29     
+ Misses       2348     2341       -7     

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[kiri11]

This seems like an improvement, thank you. It's really hard to catch a specific Exception, I have to rely on its message. I hope this gets merged.

[zsol]

Thanks for this! I've got a few minor comments but overall looks great!

[zsol]

This should go in _exceptions.py, and please write a docstring

[zaicruvoir1rominet]

Thanks for the review !

I'm going to need help on this one though:

• It's in a separate _excep.py file, since _exceptions.py already imports internals, which in turn may raise a CSTLogicError.
  Do you see any other ways than my (I admit lazy) solution in order to avoid circular import errors ?
• For the docstring, I couldn't think of anything meaningful, other than "Well... it's a CST Logic error", which doesn't add more info or context than the original name. I'd be glad to add a real doc if you have something better in mind :)

[zaicruvoir1rominet]

@zsol
Any updates ?

[zsol]

_exceptions.py already imports internals, which in turn may raise a CSTLogicError.

Let's move get_expected_str out of _exceptions.py. That should help.

For the docstring, I couldn't think of anything meaningful

How about:

General purpose internal error within LibCST itself.

[zaicruvoir1rominet]

Thanks for the support @kiri11 !
You also made me realize some users were perhaps using exception messages in order to manage errors, so I kept all original Exception messages in order to avoid breaking changes.

I hope everything is now ready (apart from that CSTLogicError file location & docstring)

[kiri11]

You're welcome! (although I didn't do anything)
Keeping the exception messages backwards-compatible is a great idea, thank you!