The trigger below calls a class. The purpose of the whole thing is to create a new custom object record when an opp is created or edited to meet a few criteria.

The thing works in the ui on single records, and I also ran bulk inserts and updates and it all works.

Problem is I'm going to deploy to prod, and I'm getting an error telling me that it's "attempting to de-reference a null object".

Does anyone see how or where this error is in the trigger or class, and how it could be resolved?  I have spent like all day trying to get past this error and no matter what I do I keep getting it.

Trigger:

trigger OpportunityTrigger on Opportunity(after insert,after update){

if (Trigger.isAfter) {

          /* BEGIN Services Engagement  Auto-create Processing for Opps */

           ServicesEngagementManager newSEOnOppInsert = new ServicesEngagementManager();

           if(Trigger.isInsert){
                newSEOnOppInsert.createEngagementWhenNeededOnOppInsert(Trigger.new);
           }

           ServicesEngagementManager newSEOnOppUpdate = new ServicesEngagementManager();

           if(Trigger.isUpdate){
                newSEOnOppUpdate.createEngagementWhenNeededOnOppUpdate(Trigger.new, Trigger.oldMap);
            }
  
            /* END Services Engagement  Auto-create Processing */

...

}

Class:

public class ServicesEngagementManager{

    public void createEngagementWhenNeededOnOppInsert(List<Opportunity> opportunities)
    {

        List<Opportunity> opps = [SELECT Id,Services_to_be_Delivered_by__c,Owner.Id,Probability,Threshold__c,Account.Id,Account.Name,Region__c,
                                                       CreatedById,Account.Region__r.OwnerId,Account.Region__r.RSA_Manager__r.Id,Professional_Services__c, 
                                                       Name From Opportunity WHERE id IN:Opportunities];
        List< SFL5_Projects__c> engagementsToCreate = new List<SFL5_Projects__c>();

        for(Opportunity opp: opps)
            if((opp.Probability>=75 && opp.Services_to_be_Delivered_by__c.contains('Training Team')) || (opp.Probability>=50 && 
                (opp.Services_to_be_Delivered_by__c.contains('Global Client Services')||opp.Services_to_be_Delivered_by__c.contains('Partner') ||  
                 opp.Services_to_be_Delivered_by__c.contains('Regional personnel')   )))   
        {
               SFL5_Projects__c engagementToAdd = new SFL5_Projects__c();

               if(opp.Account.Region__r.RSA_Manager__r.Id!=null &&  opp.Account.Region__c !=null){
               engagementToAdd.OwnerId = opp.Account.Region__r.RSA_Manager__r.Id;
                } else{
                   engagementToAdd.OwnerId = opp.Owner.Id;
                }
                engagementToAdd.Name = 'Services Engagement for: '+ opp.Account.Name;
                engagementToAdd.Opportunity__c = opp.Id;
                engagementToAdd.Client__c = opp.AccountId;
                engagementToAdd.Region__c = opp.Region__c;
                engagementToAdd.Project_Status__c = 'Active';
                engagementToAdd.Services_Amount__c = opp.Professional_Services__c;
                engagementToAdd.Services_to_be_Delivered_by__c = opp.Services_to_be_Delivered_by__c;
                engagementsToCreate.add(engagementToAdd);
         }
           insert engagementsToCreate;        
    }
   
    public void createEngagementWhenNeededOnOppUpdate(List<Opportunity> opportunities, Map<Id, Opportunity> oldMap)
    {
        List<Opportunity> opps = [SELECT Id, Threshold__c,Account.Id,Account.Name,Region__c,CreatedById,Account.Region__r.OwnerId,
                                                       Account.Region__r.RSA_Manager__r.Id,Professional_Services__c, Name From Opportunity WHERE id IN:Opportunities];
        List< SFL5_Projects__c > engagementsToCreate = new List< SFL5_Projects__c >();

        for(Opportunity opp: opportunities)
        {
            Opportunity beforeUpdate = oldMap.get(opp.Id);
            if(opp.Threshold__c=='1' && beforeUpdate.Threshold__c!='1')
           {
               SFL5_Projects__c engagementToAdd = new SFL5_Projects__c();
               
               if(opp.Account.Region__r.RSA_Manager__r.Id!=null)
               {
                  engagementToAdd.OwnerId = opp.Account.Region__r.RSA_Manager__r.Id;
                } else{
                   engagementToAdd.OwnerId = opp.OwnerId;
                }
                   engagementToAdd.Name = 'Services Engagement for: '+ opp.Account.Name;
                   engagementToAdd.Opportunity__c = opp.Id;
                   engagementToAdd.Client__c = opp.AccountId;
                   engagementToAdd.Region__c = opp.Region__c;
                   engagementToAdd.Project_Status__c = 'Active';
                   engagementToAdd.Services_Amount__c = opp.Professional_Services__c;
                   engagementsToCreate.add(engagementToAdd);
               }
         }

           insert engagementsToCreate; 
    }

}