Rational
We have a case where a company has diferent warehouses which can send products to any locations. Most of the time they produce on demand (but they may have some products on stock) so after the customer order is received they decide from which warehouse they will send (and produce if required) the goods.
Currently an error is raised then a warehouse is not set on quotation but AFAIU it is not required until the sale is proceesed because at this time the shipments (which are related to the sale are processed).
Proposal
I think we should allow to create a sale without warehouse, and prevent confirming them if the warehouse is not set. The user will be able to search the confirmed sales, set it’s warehouse and then process them manually.