I checked and the file is OK.
Dart 1.23.0 AngularDart 3.1.0
The error I am getting is:
Target of URI hasn't been generated: 'file.g.dart'
It may help to run "Synchronize" -- bound by default to Ctrl-Q.
You can restart the analyzer on the dart analysis tab, in the top left is a button with arrows running in a circle, if you hover over it it says 'Restart Dart Analysis Server'.