[FIX] point_of_sale: keyerror due to already reconciled entries

1. Install PoS and Accounting
2. In the PoS setting activate the Invoicing option
3. Sell an item X with Invoice toggle to client Y and pay it
4. Sell the same item X with Invoice toggle to the same client Y with
quantity -1
5. Close the PoS session

Traceback wil occur when trying to Validate Closing & Post Entries
because in '_create_invoice_receivable_lines' already reconciled lines
are already filtered out so invoice_receivable_lines is empty

opw-2206625

closes odoo/odoo#49407

X-original-commit: e9f5e2b7fdd332ca0fc0f43c839118ef82d4eddb
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/point_of_sale/models/pos_session.py

@@ -648,7 +648,7 @@ class PosSession(models.Model):
         # reconcile invoice receivable lines
         for account_id in order_account_move_receivable_lines:
             ( order_account_move_receivable_lines[account_id]
-            | invoice_receivable_lines[account_id]
+            | invoice_receivable_lines.get(account_id, self.env['account.move.line'])
             ).reconcile()
 
         # reconcile stock output lines