simple node-sass update which fixes this issue
@@ -36,7 +36,7 @@
"grunt-sass": "^3.0.2",
"grunt-zip": "~0.17.1",
"load-grunt-tasks": "^4.0.0",
- "node-sass": "^4.11.0",
+ "node-sass": "^4.12.0",
"mustache": "^2.3.0",
"socket.io": "^2.2.0"
},