chore: remove uses of obsolete golang.org/x/xerrors (#1776)

go1.13 and up now provide this functionality, and the xerrors.Is() function was deprecated.

Removing the dependency, as it was only used in a test.

go.mod

@@ -12,7 +12,6 @@ require (
 	golang.org/x/net v0.0.0-20221014081412-f15817d10f9b
 	golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783
 	golang.org/x/sync v0.1.0
-	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2
 	google.golang.org/appengine v1.6.7
 	google.golang.org/genproto v0.0.0-20221206210731-b1a01be3a5f6
 	google.golang.org/grpc v1.51.0

go.sum

@@ -98,8 +98,6 @@ golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 h1:H2TDz8ibqkAF6YGhCdN3jS9O0/s90v0rJh3X/OLHEUk=
-golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2/go.mod h1:K8+ghG5WaK9qNqU5K3HdILfMLy1f3aNYFI/wnl100a8=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/appengine v1.6.7 h1:FZR1q0exgwxzPzp/aF+VccGrSfxfPpkBqjIIEq3ru6c=

internal/gensupport/send_test.go

@@ -6,10 +6,9 @@ package gensupport
 
 import (
 	"context"
+	"errors"
 	"net/http"
 	"testing"
-
-	"golang.org/x/xerrors"
 )
 
 func TestSendRequest(t *testing.T) {
@@ -35,7 +34,7 @@ func TestSendRequestWithRetry(t *testing.T) {
 type brokenRoundTripper struct{}
 
 func (t *brokenRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
-	return nil, xerrors.New("this should not happen")
+	return nil, errors.New("this should not happen")
 }
 
 func TestCanceledContextDoesNotPerformRequest(t *testing.T) {
@@ -47,7 +46,7 @@ func TestCanceledContextDoesNotPerformRequest(t *testing.T) {
 		ctx, cancel := context.WithCancel(context.Background())
 		cancel()
 		_, err := SendRequestWithRetry(ctx, &client, req, nil)
-		if !xerrors.Is(err, context.Canceled) {
+		if !errors.Is(err, context.Canceled) {
 			t.Fatalf("got %v, want %v", err, context.Canceled)
 		}
 	}