Makes pkg/errors a thin compatibility layer that re-exports from pkg/log.
All error handling functions now have canonical implementations in pkg/log.
Migration guide in package documentation:
- errors.Error -> log.Err
- errors.E -> log.E
- errors.Code -> log.NewCode
- errors.New -> log.NewError
Fixes behavior consistency:
- E(op, msg, nil) now creates an error (for errors without cause)
- Wrap(nil, op, msg) returns nil (for conditional wrapping)
- WrapCode returns nil only when both err is nil AND code is empty
Closes#128
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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