Fix mypy type error in validate_batch_audio_files return type

[Copilot]

CI was failing due to a mypy type error: the function signature declared List[Tuple[Path, str]] for invalid_files, but the early-return path yields (None, str) when the directory doesn't exist.

Changes

• aiaa/audio_validation.py
  • Return type updated: List[Tuple[Path, str]] → List[Tuple[Optional[Path], str]]
  • Added explicit type annotations to valid_files and invalid_files locals — required so mypy doesn't re-infer a narrower type from the append calls and re-flag the return

# Before
) -> Tuple[List[Path], List[Tuple[Path, str]]]:
    valid_files = []
    invalid_files = []
    if not directory.exists():
        return [], [(None, f"Directory does not exist: {directory}")]  # ← type error

# After
) -> Tuple[List[Path], List[Tuple[Optional[Path], str]]]:
    valid_files: List[Path] = []
    invalid_files: List[Tuple[Optional[Path], str]] = []
    if not directory.exists():
        return [], [(None, f"Directory does not exist: {directory}")]  # ← valid

Original prompt

Fix CI errors and rerun CI until it works

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[ajprice16]

[Copilot]

Pull request overview

This PR fixes a mypy type error in validate_batch_audio_files by making the invalid_files return type accurately reflect the (None, str) early-return case when the target directory doesn’t exist.

Changes:

• Updated invalid_files return type to List[Tuple[Optional[Path], str]] to match actual behavior.
• Added explicit local type annotations for valid_files / invalid_files to keep mypy from narrowing types based on append() usage.

[Copilot]

The docstring below still describes invalid_files as containing (Path, message) tuples, but the function now returns List[Tuple[Optional[Path], str]] (and can return (None, ...) when the directory is missing). Please update the docstring lines that mention (Path, ...) so it matches the actual return type and behavior.