fix: treat typed nils as nil in Wrap/WrapPrefix#51
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Wrap and WrapPrefix only checked e == nil, so a nil pointer of a concrete error type (typed nil) was still wrapped. Calling Error() on that pointer then panicked. Use reflection to detect nilable kinds and return nil for typed nils. Fixes go-errors#35
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Summary
Wrap/WrapPrefixonly checkede == nil. A typed nil (var err *MyError) is a non-nil interface value in Go, so it was still wrapped. CallingError()on the nil pointer then panics.Fix
Add
isNilviareflectfor nilable kinds (Ptr,Slice,Map,Func,Chan,Interface) and use it inWrap/WrapPrefix.Zero-value structs that implement
errorare still wrapped (they are not nil).Test plan
TestWrapTypedNil(with examples temporarily ignored locally due to pre-existing Example* vet issues on newer Go)Fixes #35