refactor(grpc-proxy): use Metadata.Err() method to get upstream error for a broadcasted request

pkg/api/image.go

@@ -1,7 +1,6 @@
 package api
 
 import (
-	"errors"
 	"slices"
 
 	"github.com/distribution/reference"
@@ -25,14 +24,6 @@ type MachineImages struct {
 	ContainerdStore bool
 }
 
-// Error returns a non-nil error if listing images on this machine failed.
-func (mi MachineImages) Error() error {
-	if mi.Metadata != nil && mi.Metadata.Error != "" {
-		return errors.New(mi.Metadata.Error)
-	}
-	return nil
-}
-
 // ImageFilter defines criteria to filter images in ListImages.
 type ImageFilter struct {
 	// Machines filters images to those present on the specified machines (names or IDs).