[VOL-4119] voltha-lib-go incorrect argument handling for onu sw upgrade

Change-Id: Ic0b7120de69cb3d93e014709f003fd3816bdcf0c
diff --git a/VERSION b/VERSION
index e91d9be..eda862a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.3.3
+4.3.4
diff --git a/pkg/adapters/common/request_handler.go b/pkg/adapters/common/request_handler.go
index 020e799..b6cf1c0 100644
--- a/pkg/adapters/common/request_handler.go
+++ b/pkg/adapters/common/request_handler.go
@@ -852,8 +852,6 @@
 				logger.Warnw(ctx, "cannot-unmarshal-device", log.Fields{"error": err})
 				return nil, err
 			}
-		default:
-			return nil, errors.New("invalid argument")
 		}
 	}
 	return &deviceDownloadImageReq, nil
@@ -875,8 +873,6 @@
 				logger.Warnw(ctx, "cannot-unmarshal-device", log.Fields{"error": err})
 				return nil, err
 			}
-		default:
-			return nil, errors.New("invalid argument")
 		}
 	}
 	return &deviceImageReq, nil
@@ -894,10 +890,13 @@
 				logger.Warnw(ctx, "cannot-unmarshal-device", log.Fields{"error": err})
 				return "", err
 			}
-		default:
-			return "", errors.New("invalid argument")
 		}
 	}
+
+	if deviceId.Val == "" {
+		return "", errors.New("invalid argument")
+	}
+
 	return deviceId.Val, nil
 }