Handle events without alarmList during migration
Handle events without alarmList during migration

Only happens with events created after removing the old alarm code, but
especially during development it's nice to be able to run the migration
again!

mvidalgarcia/indico,indico/indico,ThiefMaster/indico,mic4ael/indico,mic4ael/indico,indico/indico,ThiefMaster/indico,OmeGak/indico,mic4ael/indico,OmeGak/indico,mvidalgarcia/indico,mvidalgarcia/indico,DirkHoffmann/indico,DirkHoffmann/indico,pferreir/indico,pferreir/indico,DirkHoffmann/indico,pferreir/indico,DirkHoffmann/indico,mic4ael/indico,OmeGak/indico,indico/indico,OmeGak/indico,ThiefMaster/indico,mvidalgarcia/indico,pferreir/indico,indico/indico,ThiefMaster/indico