Suggestions for the group picker aren't displayed correctly

Steps to reproduce:

1. Create a new application with the App Within Minutes wizard
2. In the second step add a "group picker" field
3. Add a new entry to your app and begin writing in the Group field (for example start writing "admin")

This bug is also reproduced on the "Send Message" gadget. Because of this bug you're unable to send a message to a group. I got this message when trying to send a message to a group using the gadget: "Failed to send message: Forbidden". I've added a screenshot. This is the console error:

2013-06-17 16:41:48,651 [http://192.168.0.40:8080/xwiki/bin/get/torer/da?xpage=uorgsuggest&uorg=group&input=ad] ERROR o.x.v.i.DefaultVelocityEngine  - Left side ($profileDoc.attachmentList.size()) of '>' operation has null value at /templates/macros.vm[line 227, column 67]