backend: replace /pkg/errors with errutil (#17065)

pkg/util/errutil/errors.go

@@ -1,11 +1,29 @@
 package errutil
 
-import "golang.org/x/xerrors"
+import (
+	"fmt"
+
+	"golang.org/x/xerrors"
+)
 
 // Wrap is a simple wrapper around Errorf that is doing error wrapping. You can read how that works in
 // https://godoc.org/golang.org/x/xerrors#Errorf but its API is very implicit which is a reason for this wrapper.
 // There is also a discussion (https://github.com/golang/go/issues/29934) where many comments make arguments for such
 // wrapper so hopefully it will be added in the standard lib later.
 func Wrap(message string, err error) error {
+	if err == nil {
+		return nil
+	}
+
 	return xerrors.Errorf("%v: %w", message, err)
 }
+
+// Wrapf is a simple wrapper around Errorf that is doing error wrapping
+// Wrapf allows you to send a format and args instead of just a message.
+func Wrapf(err error, message string, a ...interface{}) error {
+	if err == nil {
+		return nil
+	}
+
+	return Wrap(fmt.Sprintf(message, a...), err)
+}