Add the table of content dependency

app/index.js

@@ -146,6 +146,12 @@ async function main() {
     require('@jupyterlab/terminal-extension'),
     require('@jupyterlab/theme-light-extension'),
     require('@jupyterlab/theme-dark-extension'),
+    require('@jupyterlab/toc-extension').default.filter(({ id }) =>
+      [
+        '@jupyterlab/toc-extension:registry',
+        '@jupyterlab/toc-extension:tracker'
+      ].includes(id)
+    ),
     require('@jupyterlab/translation-extension'),
     // Add the "Hub Control Panel" menu option when running in JupyterHub
     require('@jupyterlab/collaboration-extension'),

app/package.json

@@ -140,6 +140,7 @@
     "@jupyterlab/terminal-extension": "^4.0.0-alpha.14",
     "@jupyterlab/theme-dark-extension": "^4.0.0-alpha.14",
     "@jupyterlab/theme-light-extension": "^4.0.0-alpha.14",
+    "@jupyterlab/toc-extension": "^6.0.0-alpha.14",
     "@jupyterlab/tooltip-extension": "^4.0.0-alpha.14",
     "@jupyterlab/translation-extension": "^4.0.0-alpha.14",
     "@jupyterlab/vega5-extension": "^4.0.0-alpha.14"

packages/application/src/shell.ts

@@ -75,6 +75,7 @@ export class NotebookShell extends Widget implements JupyterFrontEnd.IShell {
     } else {
       this.layout = this.initLayoutWithoutSidePanels();
     }
+
   }
 
   initLayoutWithoutSidePanels(): Layout {
@@ -263,14 +264,14 @@ export class NotebookShell extends Widget implements JupyterFrontEnd.IShell {
         if (this.sidePanelsVisible()) {
           return this._leftHandler.addWidget(widget, rank);
         }
-        throw new Error(`${area} area is not available on this page`);
+        console.warn(`${area} area is not available on this page`);
       case 'right':
         if (this.sidePanelsVisible()) {
           return this._rightHandler.addWidget(widget, rank);
         }
-        throw new Error(`${area} area is not available on this page`);
+        console.warn(`${area} area is not available on this page`);
       default:
-        throw new Error(`Cannot add widget to area: ${area}`);
+        console.warn(`Cannot add widget to area: ${area}`);
     }
   }