fix(opportunity): add validation for positive item quantities

(cherry picked from commit c47cc37441)

erpnext/crm/doctype/opportunity/opportunity.py

@@ -132,6 +132,7 @@ class Opportunity(TransactionBase, CRMNote):
 		self.validate_uom_is_integer("uom", "qty")
 		self.validate_cust_name()
 		self.map_fields()
+		self.validate_qty()
 		self.set_exchange_rate()
 
 		if not self.title:
@@ -142,6 +143,15 @@ class Opportunity(TransactionBase, CRMNote):
 	def on_update(self):
 		self.update_prospect()
 
+	def validate_qty(self):
+		for item in self.items:
+			if item.qty <= 0:
+				frappe.throw(
+					_("Row #{0}: Quantity must be greater than 0 for Item {1}").format(
+						item.idx, item.item_code
+					)
+				)
+
 	def map_fields(self):
 		for field in self.meta.get_valid_columns():
 			if not self.get(field) and frappe.db.field_exists(self.opportunity_from, field):