Clean up.

src/common/instancetracker.ts

@@ -46,7 +46,7 @@ interface IInstanceTracker<T extends Widget> {
   /**
    * A signal emitted when a widget is added or removed from the tracker.
    */
-  changed: ISignal<this, 'add' | 'remove'>;
+  readonly changed: ISignal<this, 'add' | 'remove'>;
 
   /**
    * A signal emitted when the current widget changes.
@@ -54,17 +54,17 @@ interface IInstanceTracker<T extends Widget> {
    * #### Notes
    * If the last widget being tracked is disposed, `null` will be emitted.
    */
-  currentChanged: ISignal<this, T>;
+  readonly currentChanged: ISignal<this, T>;
 
   /**
    * The current widget is the most recently focused widget.
    */
-  currentWidget: T;
+  readonly currentWidget: T;
 
   /**
    * The number of widgets held by the tracker.
    */
-  size: number;
+  readonly size: number;
 
   /**
    * Iterate through each widget in the tracker.

src/console/plugin.ts

@@ -154,9 +154,7 @@ function activateConsole(app: JupyterLab, services: IServiceManager, rendermime:
   command = 'console:create-new';
   commands.addCommand(command, {
     label: 'Start New Console',
-    execute: () => {
-      commands.execute('console:create', { });
-    }
+    execute: () => commands.execute('console:create', { })
   });
   palette.addItem({ command, category });
   menu.addItem({ command });
@@ -222,7 +220,7 @@ function activateConsole(app: JupyterLab, services: IServiceManager, rendermime:
       if (current) {
         let kernel = current.content.session.kernel;
         if (kernel) {
-          kernel.interrupt();
+          return kernel.interrupt();
         }
       }
     }
@@ -260,9 +258,7 @@ function activateConsole(app: JupyterLab, services: IServiceManager, rendermime:
       path = `${path}/console-${count}-${utils.uuid()}`;
 
       // Get the kernel model.
-      return manager.ready.then(() => {
-        return getKernel(args, name);
-      }).then(kernel => {
+      return manager.ready.then(() => getKernel(args, name)).then(kernel => {
         if (!kernel || (kernel && !kernel.id && !kernel.name)) {
           return;
         }

src/imagewidget/widget.ts

@@ -1,10 +1,6 @@
 // Copyright (c) Jupyter Development Team.
 // Distributed under the terms of the Modified BSD License.
 
-import {
-  Kernel
-} from '@jupyterlab/services';
-
 import {
   Message
 } from 'phosphor/lib/core/messaging';