Fix error in kernels sidebar when switching kernels, remove unused pr…

…op (#16188)

* Do not crash if there are no sessions for kernel

* Revert snapshot incorrectly updated in #16046

* Remove unused private `shutdownAllLabel` prop from `List` and `ListWidget`

packages/running-extension/src/kernels.tsx

@@ -325,13 +325,17 @@ namespace Private {
 
     private get _summary(): string {
       const children = this.children;
-      return children.length == 1
-        ? children[0].label()
-        : this.trans.__(
-            '%1 and %2 more',
-            children[0].label(),
-            children.length - 1
-          );
+      if (children.length === 0) {
+        return this.trans.__('No sessions connected');
+      } else if (children.length == 1) {
+        return children[0].label();
+      } else {
+        return this.trans.__(
+          '%1 and %2 more',
+          children[0].label(),
+          children.length - 1
+        );
+      }
     }
   }
 

packages/running/src/index.tsx

@@ -305,7 +305,6 @@ function List(props: {
   child?: boolean;
   runningItems: IRunningSessions.IRunningItem[];
   shutdownLabel?: string | ((item: IRunningSessions.IRunningItem) => string);
-  shutdownAllLabel?: string;
   shutdownItemIcon?: LabIcon;
   filter?: (item: IRunningSessions.IRunningItem) => Partial<IScore> | null;
   translator?: ITranslator;
@@ -420,7 +419,6 @@ class ListWidget extends ReactWidget {
     private _options: {
       manager: IRunningSessions.IManager;
       runningItems: IRunningSessions.IRunningItem[];
-      shutdownAllLabel: string;
       filterProvider?: IFilterProvider;
       translator?: ITranslator;
       collapseToggled: ISignal<Section, boolean>;
@@ -461,7 +459,6 @@ class ListWidget extends ReactWidget {
               <List
                 runningItems={options.runningItems}
                 shutdownLabel={options.manager.shutdownLabel}
-                shutdownAllLabel={options.shutdownAllLabel}
                 shutdownItemIcon={options.manager.shutdownItemIcon}
                 filter={options.filterProvider?.filter}
                 translator={options.translator}
@@ -539,7 +536,6 @@ class Section extends PanelWithToolbar {
     this.addWidget(
       new ListWidget({
         runningItems,
-        shutdownAllLabel: this._shutdownAllLabel,
         collapseToggled: this._collapseToggled,
         ...options
       })