ensure namespace placeholder reflects what will be saved to local storage (#4176)

src/renderer/components/+namespaces/namespace-select-filter.tsx

@@ -37,15 +37,15 @@ const Placeholder = observer((props: PlaceholderProps<any, boolean>) => {
   const getPlaceholder = (): React.ReactNode => {
     const namespaces = namespaceStore.contextNamespaces;
 
-    switch (namespaces.length) {
-      case 0:
-      case namespaceStore.allowedNamespaces.length:
+    if (!namespaceStore.selectedNamespaces.length || !namespaces.length) {
       return <>All namespaces</>;
-      case 1:
-        return <>Namespace: {namespaces[0]}</>;
-      default:
-        return <>Namespaces: {namespaces.join(", ")}</>;
     }
+
+    if (namespaces.length === 1) {
+      return <>Namespace: {namespaces[0]}</>;
+    }
+
+    return <>Namespaces: {namespaces.join(", ")}</>;
   };
 
   return (