NPE when displaying properties for non-existing user

Description

This fixes a NPE that can present itself on the User Properties screen

Steps to reproduce:
Attempt to view the User Properties for a user that does not exist, e.g. by accessing http://:9090/user-properties.jsp?username=foobar

Expected results
An indication is presented that the requested user does not exist

Actual results
A stack trace is presented
Exception:

Environment

None
Fixed

Assignee

Guus der Kinderen

Reporter

Greg Thomas