[FIX] product_historical_margin: do not crash if an invoice line has not related product (lp:c2c-addons/6.1  rev 28.3.26)
[FIX] product_historical_margin: do not crash if an invoice line has not related product
(lp:c2c-addons/6.1  rev 28.3.26)

Endika/margin-analysis,bmya/margin-analysis,VitalPet/margin-analysis,acsone/margin-analysis,Antiun/margin-analysis