fix: [UI filtering] be sure that '0' is not interpreted as empty.
fix: [UI filtering] be sure that '0' is not interpreted as empty.

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