Client script getOptions() issue (field choices not resetting when changing onChange field)

[Bhojraj Chauhan]

I have create an onChange client script on 'type' field with the logic to display choices in choice field 'suspension_reason'. 

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        return;
    }
  
    //Type appropriate comment here, and begin script below
    var internal1 = g_scratchpad.internalreasons;
    var external1 = g_scratchpad.externalreasons;
    var type1 = g_form.getValue('type');

    internal1 = internal1.split(',');
    external1 = external1.split(',');
    // Add the appropriate options based on the selected type
    if (type1 == 'Internal Suspend') {
        g_form.setValue('your_choice_field', '');
        for (var j1 = 0; j1 < external1.length; j1++) {
            g_form.removeOption('suspension_reason', external1[j1]);
        }
        for (var k1 = 0; k1 < internal1.length; k1++) {
            g_form.addOption('suspension_reason', internal1[k1]);
        }
    } else if (type1 == 'External Suspend') {
        g_form.setValue('your_choice_field', '');
        for (var l1 = 0; l1 < internal1.length; l1++) {
            g_form.removeOption('suspension_reason', internal1[l1]);
        }
        for (var m1 = 0; m1 < external1.length; m1++) {
            g_form.addOption('suspension_reason', external1[m1]);
        }
    }
    g_form.clearValue('suspension_reason');
}

Here, 

When I select type as Internal Suspend, the choices in suspension_reason fields show correctly. But when I change the type from Internal Suspend to External Suspend, the choices show 'None'. 
Same happens vice versa, when I select External Suspend, the choices in suspension_reason show properly, but when I reselect the type field as Internal Suspend, the choices show 'None'. 
What changes can I make to make it work as expected.
I have tried adding  g_form.clearOptions('suspension_reason'); before if/else if conditions doesnt work. 
Please drop if you guys have any suggestions to make.