XML view is broken in JIRA 4: NPE and getCustomFieldXML (when there are Perfoce-related fields)

Reproduction sequence:
1. Install JIRA 4 beta 5
2. Add custom fields of every possible type to the configuration (22 standard types)
3. Create a couple of issues
4. Open issue navigator showing this issues and select XML view

The result is the XML with an exception instead of content. I'm attaching the full page source.
This is critical problem for JIRA Client, and probably other remote clients! Without XML view, we cannot search in JIRA.