[FIX] allows to create a refund on lines without product_id
[FIX] allows to create a refund on lines without product_id

Endika/rma,eezee-it/rma,damdam-s/rma,credativUK/rma,eezee-it/rma,open-synergy/rma,ddico/rma,open-synergy/rma,Endika/rma,raycarnes/rma,gurneyalex/rma,ddico/rma,rschnapka/rma