Fix SIGSEGV in S3StorageInteractor.ListPath.

When source S3 bucket have been deleted we receive SignatureDoesNotMatch error when trying to
list objects in bucket. This error wasn't handled properly, so it lead to nil-reference dereference
in next line. (Also, yp-client showed `failed to read params: EOF` to client)

pkg/proc/interaction.go

@@ -121,7 +121,7 @@ func ProcessPutExtended(
 					return
 				} else if n != int(msg.Sz) {
 
-					_ = ycl.ReplyError(fmt.Errorf("unfull write"), "failed to compelete request")
+					_ = ycl.ReplyError(fmt.Errorf("unfull write"), "failed to complete request")
 
 					return
 				}
@@ -177,7 +177,7 @@ func ProcessListExtended(msg message.ListMessage, s storage.StorageInteractor, c
 
 	objectMetas, err := s.ListPath(msg.Prefix)
 	if err != nil {
-		_ = ycl.ReplyError(fmt.Errorf("could not list objects: %s", err), "failed to compelete request")
+		_ = ycl.ReplyError(fmt.Errorf("could not list objects: %s", err), "failed to complete request")
 
 		return nil
 	}

pkg/storage/s3storage.go

@@ -166,6 +166,7 @@ func (s *S3StorageInteractor) ListPath(prefix string) ([]*object.ObjectInfo, err
 		out, err := sess.ListObjectsV2(input)
 		if err != nil {
 			fmt.Printf("list error: %v\n", err)
+			return nil, err
 		}
 
 		for _, obj := range out.Contents {