fix: Correct argv.index() error handling in train.py

[hobostay]

Summary

Fixes incorrect error handling in argument parsing logic in train.py.

Problem

The code at line 41-43 has a bug where argv.index() is used incorrectly:

training_type_index = argv.index("--training_type")
if training_type_index == -1:
    raise ValueError("Training type not provided in command line arguments.")

Issues:

1. Unreachable code: Python's list.index() method raises ValueError when the item is not found - it never returns -1. This means the if training_type_index == -1: check is unreachable dead code.

2. Missing error handling: When --training_type is not provided, the code raises an unhandled ValueError from .index() with the generic message "'--training_type' is not in list", which doesn't clearly explain what the user should do.

3. Potential IndexError: Line 45 accesses argv[training_type_index + 1] without checking if that index exists. If --training_type is the last argument, this would raise IndexError: list index out of range.

Solution

Wrap the .index() call in a try/except block and add validation for the argument value:

try:
    training_type_index = argv.index("--training_type")
except ValueError:
    raise ValueError("Training type not provided in command line arguments. Use --training_type <type>")

if training_type_index + 1 >= len(argv):
    raise ValueError("Training type value is missing after --training_type argument.")

training_type = argv[training_type_index + 1]

Benefits:

1. Correct error handling: Properly catches the ValueError from .index()
2. Clearer error messages: Users get actionable error messages explaining what's wrong
3. Prevents IndexError: Validates that a value exists after --training_type
4. Removes dead code: Eliminates the unreachable if training_type_index == -1 check

Impact

• Low risk: Only affects error handling code path
• Better UX: Clearer error messages help users understand what went wrong
• Robustness: Prevents potential IndexError from missing argument value

Test plan

This fix ensures that:

• Missing --training_type argument now raises clear error
• --training_type without value now raises clear error
• Normal execution path is unchanged
• Dead code removed

🤖 Generated with Claude Code