Multiple Keyerror logs when DEBUG=False

[giohappy]

The fix in GeoNode/geonode#13141 doesn't work inside a geonode project.

[Gpetrak]

@giohappy the handler500 in geonode-project wasn't working as expected because it was only defined in geonode.urls, not in the root urls.py of our main project (geonode-project). As I understand, Django only recognizes global error handlers when they are defined in the root URLConf module.
Even though geonode.urls included handler500, Django ignores it unless it's explicitly redefined in the main project’s urls.py

The corresponding PR is available here: #571