fallback to null if no data is returned

views/primary.py

@@ -113,5 +113,5 @@ class StatGraph(EntityView):
                                   (' HAVING STOP-START >= 20', _('Monthly'))):
             self.w(u'<h2>%s</h2>' % label)
             rset = self._cw.execute(rql % (constraint, constraint), {'e':entity.eid})
-            self.w(self._cw.view('plot', rset))
+            self.w(self._cw.view('plot', rset, 'null'))
         self.w(u'</div>')