Prevent errors with undefined prop

Author: imaustink

bit-docs.js

@@ -3,8 +3,11 @@ var _ = require("lodash");
 var tags = require("./tags/tags");
 
 var mergeOnto = function(prop, dest, source){
+    if(!dest[prop]) {
+        dest[prop] = {};
+    }
     if(source[prop]) {
-        dest[prop] = dest[prop].concat(source[prop])
+        dest[prop] = dest[prop].concat(source[prop]);
     }
 };