fix: check len(errors) before string conversion in udiff_coder.py

[Wei-xu293]

Summary

aider/aider/coders/udiff_coder.py

Lines 114 to 118 in f09d706

	if errors:
	errors = "\n\n".join(errors)
	if len(errors) < len(uniq):
	errors += other_hunks_applied
	raise ValueError(errors)

The errors list is converted to string before its length is compared to uniq list.

Verification

• python -m pytest tests/basic/test_coder.py