Crash when oppening products by location on latest trunk
On latest trunk, if I open products by location of a product I get the following error: ``` Traceback (most recent call last): File "/trytond/wsgi.py", line 109, in dispatch_request return endpoint(request, **request.view_args) File "/trytond/protocols/dispatcher.py", line 43, in rpc return methods.get(request.rpc_method, _dispatch)( File "/trytond/wsgi.py", line 75, in wrapper return func(request, *args, **kwargs) File "/trytond/protocols/wrappers.py", line 189, in wrapper return func(request, pool, *args, **kwargs) File "/trytond/protocols/dispatcher.py", line 196, in _dispatch result = rpc.result(meth(*c_args, **c_kwargs)) File "/trytond/model/modelsql.py", line 1722, in search tables, expression = cls.__search_query(domain, count, query, order) File "/trytond/model/modelsql.py", line 1641, in __search_query tables, expression = cls.search_domain(domain) File "/trytond/model/modelsql.py", line 1859, in search_domain expression = convert(domain) File "/trytond/model/modelsql.py", line 1855, in convert return And((convert(d) for d in ( File "/trytond/model/modelsql.py", line 1855, in <genexpr> return And((convert(d) for d in ( File "/trytond/model/modelsql.py", line 1853, in convert return Or((convert(d) for d in domain[1:])) File "/trytond/model/modelsql.py", line 1853, in <genexpr> return Or((convert(d) for d in domain[1:])) File "/trytond/model/modelsql.py", line 1846, in convert expression = field.convert_domain(domain, tables, cls) File "/trytond/model/fields/field.py", line 220, in wrapper return func(self, domain, tables, Model) File "/trytond/model/fields/function.py", line 98, in convert_domain return getattr(Model, self.searcher)(self.name, domain) File "/trytond/modules/stock/location.py", line 450, in search_quantity if operator_(getattr(location, name), operand): File "/trytond/model/fields/function.py", line 160, in __get__ return super().__get__(inst, cls) File "/trytond/model/fields/field.py", line 404, in __get__ return inst.__getattr__(self.name) File "/trytond/model/modelstorage.py", line 1807, in __getattr__ read_data = self.read(list(index.keys()), list(ffields.keys())) File "/trytond/model/modelsql.py", line 1139, in read getter_results = field.get( File "/trytond/model/fields/function.py", line 27, in wrapper return func(self, *args, **kwargs) File "/trytond/transaction.py", line 50, in wrapper return func(*args, **kwargs) File "/trytond/model/fields/function.py", line 136, in get return dict((name, call(name)) for name in names) File "/trytond/model/fields/function.py", line 136, in <genexpr> return dict((name, call(name)) for name in names) File "/trytond/model/fields/function.py", line 127, in call return on_change_with_result(self, method(records, name)) File "/trytond/modules/stock/location.py", line 409, in get_quantity and (trans_context.get('stock_date_end', datetime.date.max) TypeError: '>' not supported between instances of 'NoneType' and 'datetime.date' ```
issue