Angular2 client debugging broken

angular
1

I assume I’ve screwed up my .map file or something as I can’t do simple debugging.

My ‘Pariies-list’ constructor runs fine and looks like this.

constructor() {
    super();
    console.log('party count', Parties.find().count());
    this.subscribe('parties', () => {
      this.parties = Parties.find();
      console.log('party count', Parties.find().count());
    }, true);
  }

prints 0 and then 4 in the command line.

If I put a break point anywhere in the constructor, ‘Parties’ is not defined as far as the console is concerned.
Parties is imported correctly and the code runs fine …
I just can’t use the debugger for the imported 'Parties’
How do I get debugging in the Browser back?