Fix linker stack null reference (#590)

tmcw · web-flow · commit ab62619af843 · 2016-11-10T15:26:27.000-05:00
diff --git a/lib/output/util/linker_stack.js b/lib/output/util/linker_stack.js
@@ -40,6 +40,7 @@ function firstPass(fns, input) {
  * @returns {Function} linker method
  */
 function LinkerStack(config) {
+  config = config || {};
   this.stack = [];
 
   if (config.defaultGlobals !== false) {
