[FIX] point_of_sale: multiple invoice on same commercial partner

When you are selling with invoices to multiple partner having the same
commercial partner, you get a singleton exception.

So now we are looping on the created move lines

closes odoo#71583

X-original-commit: 369331d
Signed-off-by: pimodoo <pimodoo@users.noreply.github.com>

Author: pimodoo

addons/point_of_sale/models/pos_session.py

@@ -682,12 +682,13 @@ def _create_invoice_receivable_lines(self, data):
             invoice_receivable_vals[commercial_partner].append(self._get_invoice_receivable_vals(account_id, amounts['amount'], amounts['amount_converted'], partner=commercial_partner))
         for commercial_partner, vals in invoice_receivable_vals.items():
             account_id = commercial_partner.property_account_receivable_id.id
-            receivable_line = MoveLine.create(vals)
-            if (not receivable_line.reconciled):
-                if account_id not in invoice_receivable_lines:
-                    invoice_receivable_lines[account_id] = receivable_line
-                else:
-                    invoice_receivable_lines[account_id] |= receivable_line
+            receivable_lines = MoveLine.create(vals)
+            for receivable_line in receivable_lines:
+                if (not receivable_line.reconciled):
+                    if account_id not in invoice_receivable_lines:
+                        invoice_receivable_lines[account_id] = receivable_line
+                    else:
+                        invoice_receivable_lines[account_id] |= receivable_line
 
         data.update({'invoice_receivable_lines': invoice_receivable_lines})
         return data