Add unit tests for error handling functions:
- test_crun_error_wrap: Test error wrapping functionality
- test_crun_error_get_errno: Test errno extraction from errors
- test_libcrun_verbosity: Test verbosity get/set functions
- test_libcrun_set_log_format: Test log format validation
- test_crun_error_release_null: Test NULL handling in error release
These unit tests directly exercise error.c functions for better
coverage without needing to spawn containers.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
