initializer is not a valid compile-time constant "static const expanded = OutputStyle._("expanded");"

[patriciovergaratobar]

• Dart SDK Version Dart VM version: 2.0.0-dev.63.0 (Fri Jun 15 00:42:43 2018 +0200) on "windows_x64"
• What package(s) build_runner 0.8.3
• Windows
  When trying to compile or start my application with the command "webdev serve" I get the following error:

`

webdev serve

You have hit a bug in build_runner
Please file an issue with reproduction steps at https://github.com/dart-lang/build/issues

'package:sass/src/visitor/serialize.dart': error: line 1224 pos 27: initializer is not a valid compile-time constant
static const expanded = OutputStyle._("expanded");
^

Unhandled exception:
NoSuchMethodError: The getter 'isEmpty' was called on null.
Receiver: null
Tried calling: isEmpty
#0 Object.noSuchMethod (dart:core-patch/dart:core/object_patch.dart:46)
#1 new Trace.parse (package:stack_trace/src/trace.dart:120)
#2 CommandBase.runCore. (package:webdev/src/command/command_base.dart:101)
#3 _RootZone.runUnaryGuarded (dart:async/zone.dart:1316)
#4 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336)
#5 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
#6 _StreamController&&_SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:763)
#7 _StreamController._add (dart:async/stream_controller.dart:639)
#8 _StreamController.add (dart:async/stream_controller.dart:585)
#9 _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:165)
`

Does anybody know why?

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[jakemac53]

It looks to me like you are on a very early days Dart 2 prerelease SDK that doesn't support omitting the const keyword within const contexts, so it would have to be explicitly const OutputStyle._("expanded"); in this case.

It is possible that your sass version has a bad lower bound sdk constraint, or maybe you are overriding it to select a version which is not compatible with your sdk.

[natebosch]

Yeah this looks like there was a version of sass with an invalid SDK constraint - this was not too unusual during the -dev SDK releases. I'd recommend upgrading to a stable SDK and the latest compatible sass.