MatchError cannot be used as is to ensure a particular sentinel error is returned. #876
Description
Due to MatchError performing a deep equality check after testing for errors.Is, certain mistakes can slip past it when a test is wanting to ensure that a particular sentinel error is returned. As a simple example
var SentinelError = errors.New("some error")
Expect(errors.New("some error")).To(MatchError(SentinelError)) // passes
errors.Is(errors.New("some error"), SentinelError) // returns false
Which means if a function should, but fails to return a sentinel error, but returns an error with the same underlying string value, MatchError will not catch the bug.