Mass Update Error - Cannot read properties

Hello, I created a Client Script to implement the mass update of tasks. The code is writing below:

var teamID = getControlValue('task', 'team_id');

openWCMassUpdatePopUp();

while(1){
    // read-only field
    setControlEnabled('custom_input_xml', 'task__team_id', false);
    setControlValue('custom_input_xml', 'task__team_id', teamID);
    refreshScreen();
}

The code permits copy the team that I selected in the Task Screen to the team_id of the mass update and set the field as read-only. This way, I can change other fields in the tasks, except the team_id.

In the UI Designer, I configured the mass update in the following way:

The problem is that every time I open the mass update pop-up, this error appears:

Does anyone know how to solve this problem?

Thanks!