If err is nil it wouldn't match any given target error except for nil,
so we can return early to speed up cases where Is is used without a
preceding err != nil check.
Change-Id: Ib33cff50453fe070f06871ce8074694c81ab787b
Reviewed-on: https://go-review.googlesource.com/c/go/+/576015 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@google.com>