hello every one i have two many2many fields and one res.partner fields 

when i select res.partner so give me the saleorders of this res.partner .

and when i click on save button same record are got in the second many2many field

now the problem is when i delete one record in the secod many2many field i get this error :

Traceback (most recent call last):
  File "/home/kuldip/workspace/15/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/home/kuldip/workspace/15/odoo/http.py", line 687, in dispatch
    result = self._call_function(**self.params)
  File "/home/kuldip/workspace/15/odoo/http.py", line 359, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/home/kuldip/workspace/15/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/home/kuldip/workspace/15/odoo/http.py", line 348, in checked_call
    result = self.endpoint(*a, **kw)
  File "/home/kuldip/workspace/15/odoo/http.py", line 916, in __call__
    return self.method(*args, **kw)
  File "/home/kuldip/workspace/15/odoo/http.py", line 535, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1347, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1339, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/home/kuldip/workspace/15/odoo/api.py", line 464, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/home/kuldip/workspace/15/odoo/api.py", line 451, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/home/kuldip/workspace/15/working/wt_booking_system/models/wt_booking_system.py", line 195, in write
    vals['sale_orders'] = vals['sale_ids']
Exception

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

Traceback (most recent call last):
  File "/home/kuldip/workspace/15/odoo/http.py", line 643, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/home/kuldip/workspace/15/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
KeyError: 'sale_ids'