Do not try to set base_file metadata if it was never set before
Do not try to set base_file metadata if it was never set before

Contributes to CURA-341

Curahelper/Cura,senttech/Cura,ynotstartups/Wanhao,fieldOfView/Cura,hmflash/Cura,Curahelper/Cura,totalretribution/Cura,fieldOfView/Cura,ynotstartups/Wanhao,senttech/Cura,hmflash/Cura,totalretribution/Cura