fixed: Assertion 'val->IsString()' failed

index.js

@@ -7,7 +7,7 @@ var fs    = require('fs')
   ;
 
 module.exports = function (options) {
-  var opts = options ? options : {};
+  var opts = options || {};
 
   function nodeSass (file, cb) {
     var fileDir = path.dirname(file.path);
@@ -21,6 +21,7 @@ module.exports = function (options) {
     }
 
     if (opts.sourceComments === 'map' || opts.sourceComments === 'normal') {
+      opts.sourceMap = opts.sourceMap || '';
       opts.file = file.path;
     } else {
       opts.data = file.contents.toString();
@@ -59,7 +60,7 @@ module.exports = function (options) {
         return cb();
       }
 
-      if (typeof opts.onError === 'function') { 
+      if (typeof opts.onError === 'function') {
         opts.onError(err);
         return cb();
       }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gulp-sass",
-  "version": "0.7.2",
+  "version": "0.7.3",
   "description": "Gulp plugin for sass",
   "main": "index.js",
   "scripts": {
@@ -22,7 +22,7 @@
   },
   "dependencies": {
     "node-sass": "^0.9",
-    "gulp-util": "~2.2",
+    "gulp-util": "^3.0",
     "map-stream": "~0.1"
   },
   "devDependencies": {