fix for tha case when default namespace config is missing

support/smalltalk.js

@@ -1,7 +1,10 @@
 define("amber_vm/smalltalk", ["require", "module", "./boot"], function (require, module, boot) {
     var smalltalk = boot.smalltalk;
     smalltalk._amd_require = require;
-    smalltalk._amd_defaultNamespace = module.config().defaultNamespace;
+    var config = module.config();
+    if (config) {
+        smalltalk._amd_defaultNamespace = config.defaultNamespace;
+    }
     return  smalltalk;
 });