Follows a one app from example of my problem. The rules of app are as follow:
In my grid i have an entity called Service and another called TimeStopped. The user of this app can only launch a service or an time stopped per record. Suppose the user launched a wrong registry,instead of selecting one timestopped, selected a wrong service. When the User attempts to return the service to the default optionlabel the grid throws exception "TypeError exception: Service is null".