update processing,customer and staff

lib/pages/rates/cargo_editor.dart

@@ -105,6 +105,10 @@ class _CargoEditorState extends State<CargoEditor> {
   }
 
   _save() async {
+    if (_rateController.text == "") {
+      showMsgDialog(context, "Error", "Please insert rate");
+      return;
+    }
     setState(() {
       _isLoading = true;
     });