The practice manager asked me to turn on propercasing on the Visit Reason, so I called up act.patientClinicalEvent with Administration|Archetypes and pressed the edit button, clicked on the reason node, and pressed the Add button in the Assertion Descriptors tab. This caused an NPE error as follows:

 <error-report>
<version>1.7-SNAPSHOT</version>
<revision>5421</revision>
<message>An internal application error has occurred.</message>
<exception>
<type>java.lang.NullPointerException</type>
<stackTrace>
<trace>org.openvpms.component.business.service.archetype.helper.DescriptorHelper.getArchetypeDescriptor(DescriptorHelper.java:137)</trace>
<trace>org.openvpms.component.business.service.archetype.helper.DescriptorHelper.getArchetypeDescriptor(DescriptorHelper.java:117)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:372)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.layout.AbstractLayoutContext.getArchetypeDescriptor(AbstractLayoutContext.java:369)</trace>
<trace>org.openvpms.web.component.im.edit.AbstractIMObjectEditor.&lt;init&gt;(AbstractIMObjectEditor.java:170)</trace>
<trace>org.openvpms.web.component.im.edit.DefaultIMObjectEditor.&lt;init&gt;(DefaultIMObjectEditor.java:53)</trace>
<trace>org.openvpms.web.component.im.edit.IMObjectEditorFactory.create(IMObjectEditorFactory.java:98)</trace>
<trace>org.openvpms.web.component.im.edit.AbstractIMObjectCollectionEditor.createEditor(AbstractIMObjectCollectionEditor.java:457)</trace>


etc etc etc... 

Regards, Tim G