I've been playing with Angular2 using IntelliJ IDEA (2016.3.5) and the latest Dart plugin, and I just can't figure out where the errors, exceptions, assert failures etc. ends up.
I am running Dartium with DART_FLAGS="--checked" and pub serve seems to default to debug mode as far as I can read. Dart2js is configured to run in checked mode as well and the analysis server is configured for strong mode. I have also tried using the JetBrains Chrome extension so I get everything shown directly in IDEA, including the console saying Observatory listening at http://127.0.0.1:35517/.
When there are no errors the Angular2 Dart app runs just fine in Dartium but if I add an assert some where in the code, ie. on a button trigger, the app just stops working at that point with no error output anywhere. Same goes if there's some other error somewhere that pub serve didn't detect.
Dart and Dartium are both at the currently latest version, 1.22.1.
This will be fixed in Angular3 beta.x due to be released the next days it seems.