VOC names dictionary fix

[glenn-jocher]

Signed-off-by: Glenn Jocher [email protected]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved error handling and messaging in data loading and parsing for YOLOv5.

📊 Key Changes

• VOC.yaml Updates: Streamlined the names list creation and modified conditional checks within the dataset parser.
• File Not Found Error: Enhanced the error message clarity when no images or labels are detected by the dataset loader.
• Empty Labels Check: Added an additional assertion to prompt an error if all labels are empty during the training data preparation.
• Help URL: Updated the Help URL message format for consistency and readability in error messages throughout the dataloaders module.

🎯 Purpose & Impact

• Error Clarity: Users will receive clearer error messages, guiding them more effectively when dataset issues arise.
• Training Data Checks: The added checks ensure users are warned about potential issues with training data, such as missing labels or images, preventing confusion during model training.
• Documentation Accessibility: Updated Help URL formatting makes it easier for users to seek guidance and follow best practices when training custom models with YOLOv5.