Automatically delete members when families are deleted

geneit_app/src/widgets/AsyncWidget.tsx

@@ -13,6 +13,7 @@ export function AsyncWidget(p: {
   errMsg: string;
   build: () => React.ReactElement;
   ready?: boolean;
+  errAdditionalElement?: () => React.ReactElement;
 }): React.ReactElement {
   const [state, setState] = useState(State.Loading);
 
@@ -62,6 +63,8 @@ export function AsyncWidget(p: {
         </Alert>
 
         <Button onClick={load}>Réessayer</Button>
+
+        {p.errAdditionalElement && p.errAdditionalElement()}
       </Box>
     );