NPE when using dynamic mixins

When having added the tags metadata in the quickstart-war to myarticle1, a document is not opened in the editor.

In the logs, wicket shows the failure to edit:

Caused by: java.lang.NullPointerException
at org.hippoecm.frontend.editor.plugins.field.PropertyFieldPlugin.newPropertyModel(PropertyFieldPlugin.java:84)
at org.hippoecm.frontend.editor.plugins.field.PropertyFieldPlugin.newProvider(PropertyFieldPlugin.java:126)
at org.hippoecm.frontend.editor.plugins.field.AbstractFieldPlugin.getProvider(AbstractFieldPlugin.java:274)
at org.hippoecm.frontend.editor.plugins.field.AbstractFieldPlugin.onBeforeRender(AbstractFieldPlugin.java:259)
at org.hippoecm.frontend.editor.plugins.field.PropertyFieldPlugin.onBeforeRender(PropertyFieldPlugin.java:148)
at org.apache.wicket.Component.internalBeforeRender(Component.java:1061)
at org.apache.wicket.Component.beforeRender(Component.java:1095)
at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1727)
... 65 more

When the hippostd:taggable mixin is removed from the document, everything is fine again.