On my quote object I have a visualforce page and a trigger creates new records in several different record types, but I want to use the standard new quote record functionality for one record type. When I try to save a record wit the the standard fuctionality, I recieve the following error message:

Error: Invalid Data.
Review all error messages below to correct your data.
Apex trigger QuoteNumberUpdate caused an unexpected exception, contact your administrator: QuoteNumberUpdate: execution of AfterInsert caused by: System.NullPointerException: Attempt to de-reference a null object: Trigger.QuoteNumberUpdate: line 22, column 14

 Below is my code:

trigger QuoteNumberUpdate on Quote (after Insert) {

    Set<Id> qid = new Set<Id>();
    decimal bqn=0,fqn =0;
    for(Quote q : trigger.new){
        System.debug('**** 0 q id : '+q.id);
         qId.add(q.opportunityid);    
    }
    
    List<Opportunity> o = [select id, Next_Budget_Quote_Number__c,
                 Next_Firm_Quote_Number__c 
                 from Opportunity where id =:qid];
    
    List<Quote> qu = [select id, recordtypeid from quote where id =: qid];
    
   
    id brecordtypeid = [select id,name from RecordType where sobjecttype='Quote' 
                        and name='Budget Quote'].id;
    id frecordtypeid = [select id,name from RecordType where sobjecttype='Quote' 
                        and name='Firm Quote'].id;

    id oid = System.currentpageReference().getParameters().get('oppid');
    String Typ = System.currentpageReference().getParameters().get('Type');
    String Rec = System.currentpageReference().getParameters().get('Rec');
    System.debug('o[0].Next_Budget_Quote_Number__c'+o[0].Next_Budget_Quote_Number__c);

     try
    {
         bqn = o[0].Next_Budget_Quote_Number__c + 1;
    }
    catch(NullPointerException ex)
    {
         bqn = 1;
    }
    try
    {
         fqn = o[0].Next_Firm_Quote_Number__c + 1;
    }
    catch(NullPointerException ex)
    {
         fqn = 1;
    }
    List<recordtype> brec = [select id from recordtype where name = 'Budget Quote'];
    List<recordtype> frec = [select id from recordtype where name = 'Firm Quote'];
    
   for(Opportunity op : o){
       
       If(Rec == 'Budget Quote' ){
                    o[0].Next_Budget_Quote_Number__c = bqn ;
                    } else
       If(Rec == 'Firm Quote' ){
                    o[0].Next_Budget_Quote_Number__c = fqn ;
                    }
               }
                    update o;
    }

For the visualforce page, I am passign values through the url, but don't need the values for the standard Opportunity object. How do I solve this problem?

Thank you