Received servlet error when displaying popup wiki formatting help from comments help link. Page header displayed ok. Content displayed stack trace below:

An error occurred whilst rendering this message. Please contact the administrators, and inform them of this bug. Details: ------- java.lang.NullPointerException at org.apache.velocity.context.InternalContextAdapterImpl.get(InternalContextAdapterImpl.java:162) at org.apache.velocity.runtime.parser.node.ASTReference.getVariableValue(ASTReference.java:623) at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:151) at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:220) at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:230) at org.apache.velocity.Template.merge(Template.java:256) at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:450) at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:419) at com.atlassian.velocity.DefaultVelocityManager.getEncodedBody(DefaultVelocityManager.java:74) at com.atlassian.jira.plugin.webwork.JiraPluginWebworkVelocityServlet.service(JiraPluginWebworkVelocityServlet.java:50) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at