fix: work with sourcemaps when mocha is wrapped (#237) (#238)

* Work with source maps

 * Avoid calling callback twice

Author: tschaub

package.json

@@ -37,7 +37,7 @@
     "async": "~0.9.0",
     "loader-utils": "^0.2.5",
     "lodash": "^3.8.0",
-    "source-map": "^0.1.41",
+    "source-map": "^0.5.6",
     "webpack-dev-middleware": "^1.12.0"
   },
   "devDependencies": {

src/mocha-env-loader.js

@@ -1,19 +1,21 @@
-//var path = require('path')
-var SourceNode = require('source-map').SourceNode
+var sourceMap = require('source-map')
 var loaderUtils = require('loader-utils')
 
+var SourceNode = sourceMap.SourceNode
+var SourceMapConsumer = sourceMap.SourceMapConsumer
+
 module.exports = function(content, map) {
   this.cacheable()
 
   var sourceNode
   var id = this.options.name
 
   if (!id) {
-    this.callback(null, content, map)
+    return this.callback(null, content, map)
   }
 
   if (map) {
-    sourceNode = SourceNode.fromSourceWithMap(content, map)
+    sourceNode = SourceNode.fromStringWithSourceMap(content, new SourceMapConsumer(map))
   } else {
     var fileName = loaderUtils.getRemainingRequest(this)