fix: Fixed the empty event warning if an event only has objects but no attributes
fix: Fixed the empty event warning if an event only has objects but no attributes

FIRSTdotorg/MISP,TheDr1ver/MISP,SteveClement/MISP,MISP/MISP,devnull-/MISP,FIRSTdotorg/MISP,FloatingGhost/MISP,SteveClement/MISP,devnull-/MISP,SteveClement/MISP,TheDr1ver/MISP,devnull-/MISP,FIRSTdotorg/MISP,Rafiot/MISP,Rafiot/MISP,Rafiot/MISP,MISP/MISP,FIRSTdotorg/MISP,MISP/MISP,MISP/MISP,MISP/MISP,devnull-/MISP,FloatingGhost/MISP,TheDr1ver/MISP,Rafiot/MISP,FloatingGhost/MISP,SteveClement/MISP,FloatingGhost/MISP,SteveClement/MISP,TheDr1ver/MISP