Search fails if documents do not have the common schema

Search (and then DashBoard) fails if some matching documents do not have the common schema.

This should be at least shielded.

Partial traceback :
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:283)
at org.jboss.seam.ui.facelet.MethodExpressionHelper.invokeTheExpression(MethodExpressionHelper.java:102)
at org.jboss.seam.ui.facelet.ParamMethodExpression.invoke(ParamMethodExpression.java:62)
at com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
... 66 more
Caused by: org.nuxeo.ecm.core.query.QueryException: getDocumentModels failed
at org.nuxeo.ecm.core.jcr.JCRQueryResult.getDocumentModels(JCRQueryResult.java:297)
at org.nuxeo.ecm.core.api.AbstractSession.query(AbstractSession.java:774)
... 228 more
Caused by: java.lang.NullPointerException
at org.nuxeo.ecm.core.api.DocumentModelFactory.exportSchema(DocumentModelFactory.java:181)
at org.nuxeo.ecm.core.api.DocumentModelFactory.createDocumentModel(DocumentModelFactory.java:115)
at org.nuxeo.ecm.core.jcr.JCRQueryResult.getDocumentModels(JCRQueryResult.java:291)
... 229 more