fix(errors): correctly display string-typed errors

import.js

@@ -15,7 +15,7 @@ var wofAdminRecords = {};
 bundles.generateBundleList((err, bundlesToImport) => {
 
   if (err) {
-    throw new Error(err.message);
+    throw new Error(err.message || err);
   }
 
   // This can be either csv or db files, the read stream module will do the job