Weird problems with Ionic 2 CLI and app

I have 2 problems:
1. When I had nodejs 4.x i runned ionic serve --lab I got errors and blank app: (it's ionic conference app)

EXCEPTION: Error during instantiation of ConferenceApp!.BrowserDomAdapter.logError @ app.bundle.js:33734
app.bundle.js:33734 ORIGINAL EXCEPTION: TypeError: Cannot read property 'user:login' of undefinedBrowserDomAdapter.logError @ app.bundle.js:33734
app.bundle.js:33734 ORIGINAL STACKTRACE:BrowserDomAdapter.logError @ app.bundle.js:33734
app.bundle.js:33734 TypeError: Cannot read property 'user:login' of undefined
at Events.subscribe (app.bundle.js:41672)
at ConferenceApp.listenToLoginEvents (app.bundle.js:3265)
at new ConferenceApp (app.bundle.js:3246)
at app.bundle.js:8131
at Injector._instantiate (app.bundle.js:6696)
at Injector._instantiateProvider (app.bundle.js:6644)
at Injector._new (app.bundle.js:6633)
at InjectorInlineStrategy.instantiateProvider (app.bundle.js:6130)
at ElementInjectorInlineStrategy.hydrate (app.bundle.js:19812)
at ElementInjector.hydrate (app.bundle.js:19473)BrowserDomAdapter.logError @ app.bundle.js:33734
app.bundle.js:33734 ERROR CONTEXT:BrowserDomAdapter.logError @ app.bundle.js:33734
app.bundle.js:33734 _Context

1. When I updated to node 5.x when I runned ionic serve --lab there is no response in the terminal. nothing. even ionic serve, ionic run, no any response. I tried to update npm and everything... no solution.

2. (optional question) I had bug when i am using android in ionic 2 app and click on hardware back button, the app is exiting, even if i have back page. is it fixed?

any suggestions?