add custom error handling

[yuvimittal]

Pull Request description

How to test these changes

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Pull Request checklists

This PR is a:

• bug-fix
• new feature
• maintenance

About this PR:

• it includes tests.
• the tests are executed on CI.
• the tests generate log file(s) (path).
• pre-commit hooks were executed locally.
• this PR requires a project documentation update.

Author's checklist:

• I have reviewed the changes and it contains no misspelling.
• The code is well commented, especially in the parts that contain more
  complexity.
• New and old tests passed locally.

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## Reviewer's Checklist

- [ ] I managed to reproduce the problem locally from the `main` branch
- [ ] I managed to test the new changes locally
- [ ] I confirm that the issues mentioned were fixed/resolved .

[github-actions]

OSL ChatGPT Reviewer

NOTE: This is generated by an AI program, so some comments may not make sense.

.prettierrc.yaml

LGTM!

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src/arx/lexer.py

• Potential runtime bug: constructing the message assumes location has .line/.col. If location is None or a different object, raising LexerError will itself raise AttributeError and mask the original error. Use safe access with fallbacks. Replace the body as below (L.207):

  def init(self, message: str, location: SourceLocation) -> None:
  """Initialize LexerError with an error message and optional source location."""
  line = getattr(location, "line", "?")
  col = getattr(location, "col", "?")
  super().init(f"{message} at line {line}, col {col}")
  self.location = location

• To avoid forward-reference issues in some Python versions or when evaluating type hints at runtime, consider enabling postponed evaluation (L.1):

  from future import annotations # """Enable postponed evaluation of annotations."""

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[github-actions]

OSL ChatGPT Reviewer

NOTE: This is generated by an AI program, so some comments may not make sense.

src/arx/lexer.py

• Correctness: The numeric branch will treat a standalone '.' (or the start of '..') as a number, which can either mis-tokenize punctuation or raise later when converting ".". Guard the branch with a digit lookahead so only "." enters numeric lexing. Example change (L.322):
  if self.last_char.isdigit() or (self.last_char == "." and self.peek().isdigit()):
  If you don’t have peek(), add:
  def peek(self) -> str:
  """Peek next character without consuming it."""
  return self.source[self.index] if self.index < len(self.source) else "\0"

• Breaking behavior: Introducing LexerError changes the public contract of get_token/get_next_token. Ensure callers catch this or convert it to an error token to avoid crashing the pipeline.

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