If the user forgets to run populateSitesTable.php pollForChanges will give an error message that makes it hard to debug:
Fatal error: Call to a member function getField() on a non-object in /srv/devclient/w/extensions/Wikibase/client/includes/ClientChangeHandler.php on line 125
It would be cool to make the error message more precise or to make pollForChanges check if populateSitesTable has been run.
Version: unspecified
Severity: normal