I'm trying to close POS Session in odoo 15 but i'm get this  Error 

Traceback (most recent call last):
  File "/odoo/odoo15-server/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/odoo/odoo15-server/odoo/http.py", line 687, in dispatch
    result = self._call_function(**self.params)
  File "/odoo/odoo15-server/odoo/http.py", line 359, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/odoo/odoo15-server/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/odoo/odoo15-server/odoo/http.py", line 348, in checked_call
    result = self.endpoint(*a, **kw)
  File "/odoo/odoo15-server/odoo/http.py", line 916, in __call__
    return self.method(*args, **kw)
  File "/odoo/odoo15-server/odoo/http.py", line 535, in response_wrap
    response = f(*args, **kw)
  File "/odoo/odoo15-server/addons/web/controllers/main.py", line 1339, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/odoo/odoo15-server/addons/web/controllers/main.py", line 1327, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/odoo/odoo15-server/odoo/api.py", line 464, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/odoo/odoo15-server/odoo/api.py", line 451, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/odoo/custom/thhaba/pos_retail/models/pos/PosSession.py", line 152, in action_pos_session_closing_control
    return super(PosSession, self).action_pos_session_closing_control(balancing_account=balancing_account,
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 300, in action_pos_session_closing_control
    return session.action_pos_session_validate(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/odoo/custom/thhaba/pos_retail/models/pos/PosSession.py", line 236, in action_pos_session_validate
    return super(PosSession, self).action_pos_session_validate(balancing_account=balancing_account,
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 311, in action_pos_session_validate
    return self.action_pos_session_close(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 319, in action_pos_session_close
    return self._validate_session(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/odoo/custom/thhaba/pos_retail/models/pos/PosSession.py", line 368, in _validate_session
    res = super(PosSession, self.with_context(context))._validate_session(
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 337, in _validate_session
    data = self.with_company(self.company_id)._create_account_move(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 655, in _create_account_move
    data = self._create_cash_statement_lines_and_cash_move_lines(data)
  File "/odoo/odoo15-server/addons/point_of_sale/models/pos_session.py", line 992, in _create_cash_statement_lines_and_cash_move_lines
    statement = statements_by_journal_id[payment_method.journal_id.id]
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/odoo/odoo15-server/odoo/http.py", line 643, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/odoo/odoo15-server/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
KeyError: 18