feat(errors): report errors to the user with notifications

Author: rgbkrk

src/notebook/kernel/shutdown.js

@@ -11,7 +11,6 @@ export function cleanupKernel(kernel, closeChannels, _fs = fs) {
       kernel.channels.stdin.complete();
       kernel.channels.control.complete();
     } catch (err) {
-      // nom nom nom
       console.warn(`Could not cleanup kernel channels, have they already
         been completed?`, kernel.channels);
     }

src/notebook/middlewares.js

@@ -7,8 +7,34 @@ import * as constants from './constants';
 
 const rootEpic = combineEpics(...epics);
 
+const errorMiddleware = store => next => action => {
+  if (!action.type.includes('ERROR')) {
+    return next(action);
+  }
+  console.error(action);
+  let errorText;
+  if (action.payload) {
+    errorText = action.payload;
+  } else {
+    errorText = JSON.stringify(action, 2, 2);
+  }
+  const state = store.getState();
+  const notificationSystem = state.app.get('notificationSystem');
+  if (notificationSystem) {
+    notificationSystem.addNotification({
+      title: action.type,
+      message: errorText,
+      dismissible: true,
+      position: 'tr',
+      level: 'error',
+    });
+  }
+  return next(action);
+};
+
 const middlewares = [
   createEpicMiddleware(rootEpic),
+  errorMiddleware,
 ];
 
 export default middlewares;