check if there is a value before accessing it (#1013)
check if there is a value before accessing it (#1013)


musicEnfanthen/Knora,dhlab-basel/Knora,musicEnfanthen/Knora,dhlab-basel/Knora,dhlab-basel/Knora,dhlab-basel/Knora,musicEnfanthen/Knora,musicEnfanthen/Knora,musicEnfanthen/Knora,musicEnfanthen/Knora,dhlab-basel/Knora,musicEnfanthen/Knora,dhlab-basel/Knora,dhlab-basel/Knora