epics.ts

export const updateDisplayEpic = (
  action$: ActionsObservable<
    actions.NewKernelAction | actions.KillKernelSuccessful
  >
) =>
  // Global message watcher so we need to set up a feed for each new kernel
  action$.pipe(
    ofType(actions.LAUNCH_KERNEL_SUCCESSFUL),
    switchMap(
      (action: actions.NewKernelAction | actions.KillKernelSuccessful) =>
        (action as actions.NewKernelAction).payload.kernel.channels.pipe(
          map((msg: JupyterMessage) => ({ type: "KERNEL_MESSAGE", payload: { msg } }))),
          catchError(error =>
           console.log(error) // Wait some time and launch the kernel
          )
        )
    )
  );


/**
 * Listens to unexpected closes on the WebSocket subject connecting
 * to the client to the service then notifies the user and triggers
 * a kernel restart.
 */
const watchKernelFailure = (
  action$: ActionsObservable<nteractActions.NewKernelAction>,
  state$: any
) =>
  action$.pipe(
    ofType(nteractActions.LAUNCH_KERNEL_SUCCESSFUL),
    withLatestFrom(state$),
    switchMap(([action, state]) =>
      action.payload.kernel.channels.pipe(
        last(),
        mergeMap(() => {
          const kernel = selectors.kernelForContentRef(action.payload.contentRef);
          return of(launchkernelHere);
        }),
        takeUntil(action$.pipe(ofType(nteractActions.KILL_KERNEL_SUCCESSFUL)))
      )
    )
  );