Grunt crashes after "unexpected end of input" warning in expressServer task - OS X Yosemite, Ember App Kit

I was away from our Rails + Ember project and didn't realize that my local environment had completely broken with the upgrade to OS X Yosemite. Several steps have been fixed (like fixing / usr / local / permissions for homebrew, or getting an earlier version of Phantomjs), but now I'm stuck with Grunt for a few days and need help.

Stack

A set of Ember apps on the frontend, rails on the backend.

Problem:

running grunt server

, I get the warning as such:

...
Done, without errors.

Running "expressServer:debug" (expressServer) task
Warning: Unexpected end of input Use --force to continue.

Aborted due to warnings.

      

        
        
        
      

    

Running with a flag --verbose

does not shed light at all, exactly the same error.

By using a flag --force

, it continues to run, but does not actually serve the application.

Relevant task fromGruntfile.js

:

In fact, by default, that came from EAK :

grunt.registerTask('server', "Run your server in development mode, auto-rebuilding when files change.", function(proxyMethod) {
  var expressServerTask = 'expressServer:debug';
  if (proxyMethod) {
    expressServerTask += ':' + proxyMethod;
  }

  grunt.task.run(['clean:debug',
                  'build:debug',
                  expressServerTask,
                  'watch'
                  ]);
});

      

        
        
        
      

    

Now I am completely lost on how to debug it further. Excessive searching didn't work for me, there are no logs, and the error message doesn't guide me: --(

Any ideas on how I can get the grunt server to actually serve my application?