Store LoadingWidget message in a local variable for easy reference

src/aiidalab_qe/common/widgets.py

@@ -961,9 +961,10 @@ class LoadingWidget(ipw.HBox):
     """Widget for displaying a loading spinner."""
 
     def __init__(self, message="Loading", **kwargs):
+        self.message = ipw.Label(message)
         super().__init__(
             children=[
-                ipw.Label(message),
+                self.message,
                 ipw.HTML("<i class='fa fa-spinner fa-spin fa-2x fa-fw'/>"),
             ],
             **kwargs,