Don't pass support_angle to shader unless it is valid
Don't pass support_angle to shader unless it is valid

CURA-2058

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