Add catch for misspelled --task

[leandervaneekelen]

Signed-off-by: Leander van Eekelen 47320151+leandervaneekelen@users.noreply.github.com

Fix #10419. Makes val.py fail loudly instead of silently on a misspelled --task.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Added error handling for unsupported tasks in the validation scripts.

📊 Key Changes

• 🛠️ Introduced a new conditional statement to segment/val.py and val.py.
• 🚫 Implemented an error raise for when an undefined --task argument is used.

🎯 Purpose & Impact

• Enhanced Clarity: Users will now receive a clear error message if they try to run the validation script with an unsupported task argument.
• Preventative Measures: Prevents accidental misuse of the script, guiding users towards correct usage.
• User Experience: Improves the user experience by making the script more robust and user-friendly.

[github-actions]

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[glenn-jocher]

@leandervaneekelen PR is merged. Thank you for your contributions to YOLOv5 🚀 and Vision AI ⭐