I have a trigger that is supposed to change our Substatus depending on the Case Owner(profile or queue name)

right now it will only work if I choose a Queue or Partner user.  If I try to click Change next to Case Owner and assign the Case to a User it gives me the following error:
Error: Apex trigger CW_Update_Substatus_based_on_Case_Owner caused an unexpected exception, contact your administrator: CW_Update_Substatus_based_on_Case_Owner: execution of BeforeUpdate

caused by: System.NullPointerException: Attempt to de-reference a null object: Trigger.CW_Update_Substatus_based_on_Case_Owner: line 10, column 1

I've made this trigger as simple as possible and created 2 formula fields, one to show the queue name if the case is assigned to a queue(CW_Queue_Case_Owner__c) and one to show the profile ID if the case is assigned to a user(CW_Owner_Profile__c).  I have no idea what else could possibly be wrong.  Please help!




trigger CW_Update_Substatus_based_on_Case_Owner on Case (before update, after update)
{
        //Set<Id> ownerIds = new Set<Id>();
        for(Case objCase : Trigger.new){
                //ownerIds.add(objCase.OwnerId);
        }
  
        for (Case objCase : Trigger.new)
        {
           if(objCase.CW_Owner_Profile__c == '00e30000001aw4D'||objCase.CW_Queue_Case_Owner__c.contains('Dealer'))             
           {
                objCase.Substatus__c = 'Open with Dealer';
            }else{
                if((objCase.CW_Owner_Profile__c =='00e30000001c54i' || objCase.CW_Owner_Profile__c =='00ea0000001ds8w') || objCase.CW_Queue_Case_Owner__c.contains('T2'))              
                {
                objCase.Substatus__c = 'Open with Support Advocates';
                }else{
                    objCase.OwnerId = '00G30000001oUSL';
                    objCase.Substatus__c = 'Open with Product Specialists';
                    }
        }       
     }
}