I needed to add a validation rule to opportunities to prevent a specific type of contact from being added to the opportunity upon lead conversion.
The validation rule works as expected, but I need help cleaing up the error message. Currently it looks like this.

Validation error on Lead: LeadTrigger: execution of AfterUpdate caused by: System.DmlException: Update failed. First exception on row 0 with id 0060d00001y6mn8AAA; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, ***SORRY. THE CONTACT YOU HAVE SELECTED IS INACTIVE IN JIVA. PLEASE SELECT A DIFFERENT CONTACT OR CREATE A NEW CONTACT***: [] Trigger.LeadTrigger: line 44, column 1

I really only need the text between the asterisks.

This is the lead conversion trigger:
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trigger LeadTrigger on Lead (after update, after insert) 
{

    //JWAHLERS/FF 12/22/2016
    //Added if after update  to existing logic:
    if(trigger.isUpdate)
    {
        //List<Lead> convertedLeadsToProcess = new List<Lead>();

        Map<Id, Id> oppIdToConIdMap = new Map<Id, Id>();

        for (Lead l : (List<Lead>)Trigger.new){

            if (((Lead)trigger.oldMap.get(l.Id)).isConverted == false && l.isConverted == true
                && l.ConvertedOpportunityId != null && l.ConvertedContactId != null)
            {
                //convertedLeadsToProcess.add(l);
                oppIdToConIdMap.put(l.ConvertedOpportunityId, l.ConvertedContactId);
            }
        }



        //JW@ff: query for opportunities in opptIdSet
        if(!oppIdToConIdMap.isEmpty())
        {
            List<Opportunity> oppList = [Select Id From Opportunity Where Id IN: oppIdToConIdMap.keySet()];

            List<Opportunity> updatedOppList = new List<Opportunity>();

            for(Opportunity opp: oppList)
            {
                if(oppIdToConIdMap.containsKey(opp.Id))
                {
                    opp.Contact__c = oppIdToConIdMap.get(opp.Id);
                    updatedOppList.add(opp);
                }
            }



            if(!updatedOppList.isEmpty())
            {
                update updatedOppList;
            }
        }
    }



    //JWAHLERS/FF   12/22/2016
    //Call handler for inserts EAGSC2-51
    //DISABLED UNTIL DEVELOPMENT IS COMPLETE
    if(trigger.isInsert)
    {
        LeadTriggerHandler.handleAfterInsert(trigger.newMap);
    }





    /*if (convertedLeadsToProcess.size() > 0){

        Set<Id> OpptyIdSet = new Set<Id>();

        Set<Id> ContactIdSet = new Set<Id>();

        for(Lead l: convertedLeadsToProcess){

            OpptyIdSet.add(l.ConvertedOpportunityId);

            ContactIdSet.add(l.ConvertedContactId);

        }

        // Map<OpportunityId, Map<ContactId, OpportunityContactRole>>
        Map<Id, Map<Id, OpportunityContactRole>> oCRMap = new Map<Id, Map<Id, OpportunityContactRole>>();

        for(OpportunityContactRole oCR :[SELECT Id,IsPrimary,OpportunityId,ContactId FROM OpportunityContactRole WHERE OpportunityId IN :OpptyIdSet AND ContactId IN :ContactIdSet]){
                            
            if (oCR.IsPrimary == false){

                if(!oCRMap.containsKey(oCR.OpportunityId))
                {
                    oCRMap.put(oCR.OpportunityId, new Map<Id, OpportunityContactRole>());
                }                   

                oCRMap.get(oCR.OpportunityId).put(oCR.ContactId,oCR);
            }
        }

        Map<Id, Id> oppIdToConIdMap = new Map<Id, Id>();

        List<OpportunityContactRole> oCRToUpdate = new List<OpportunityContactRole>();

        for(Lead l: convertedLeadsToProcess){

            if (oCRMap.ContainsKey(l.ConvertedOpportunityId) && oCRMap.get(l.ConvertedOpportunityId).containsKey(l.ConvertedContactId)){

                OpportunityContactRole oCR = oCRMap.get(l.ConvertedOpportunityId).get(l.ConvertedContactId);

                oCR.IsPrimary = true;

                oCRToUpdate.add(oCR);

                //JW@ff generate map of opportunityId => contactId
                oppIdToConIdMap.put(oCR.OpportunityId, oCR.ContactId);

            }
        }

        if (oCRToUpdate.size() > 0){

            update oCRToUpdate;
        }
    }*/
}

Or do I need to update the Lead Trigger Class?