I have written a trigger that creates a contact when a quote has been accepted.  It is working in Sandbox.  Here is the code:

trigger CreateContract on Quote (before update) {
    
   for(Quote q : trigger.new){
        

        if(q.Status == 'Accepted'){
            
      Account acct = [SELECT Id, Name, BillingStreet, BillingCity, BillingState, BillingPostalCode, BillingCountry, ShippingStreet, ShippingCity, ShippingState, ShippingPostalCode, ShippingCountry FROM Account WHERE Id = :q.AccountId];
      Opportunity opp = [SELECT Id, Name, Total_MRC__c FROM Opportunity WHERE Id = :q.OpportunityId];
            
            List <Contract> co = [SELECT Id FROM Contract WHERE Opportunity__c = :opp.Id];
            List <Contract> cont = [SELECT Id FROM Contract WHERE Quote__c = :q.Id];
            if (cont.size() <= 0){

          Contract ct = new Contract();
            
            ct.AccountId = acct.Id;
            ct.Status = 'Draft';
            ct.Opportunity__c = opp.Id;
            ct.Quote__c = q.Id;
            ct.BillingStreet = acct.BillingStreet;
            ct.BillingCity = acct.BillingCity;
            ct.BillingState = acct.BillingState;
            ct.BillingPostalCode = acct.BillingPostalCode;
            ct.BillingCountry = acct.BillingCountry;
            ct.salesReach__Contract_Monthly_Billing__c = opp.Total_MRC__c;
                
            insert ct;
                
                opp.StageName = 'Contract Requested by Client';
                update opp;
            }
        }
                
    }
            
}

I am trying to write the associated test class so I can push to production.  However I keep getting failed statuses when I click "Run Test" such as:

System.DmlException: Update failed. First exception on row 0 with id 0Q01800000008xyCAA; first error:
CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, CreateContract: execution of AfterUpdate
caused by: System.QueryException: List has no rows for assignment to SObject
Trigger.CreateContract: line 8, column 1: []

Here is what I have so far for the test class:

@isTest
public class TestCreateContract {
    public static testmethod void TestUpdateChildAccounts(){
        Account a = new Account();
        a.Name = 'Test Account';
        a.salesReach__Agent_Account_Company_Name__c = '001a000001DbY9F';
        a.salesReach__Agent_Contact_Name__c = '003a000001XKLvE';
        a.BillingStreet = '1340 S Market St.';
        a.BillingCity = 'T or C';
        a.BillingState = 'NM';
        a.BillingPostalCode = '87901';
        a.BillingCountry = 'USA';
        a.ShippingStreet = '1340 S Market St.';
        a.ShippingCity = 'T or C';
        a.ShippingState = 'NM';
        a.ShippingPostalCode = '87901';
        a.ShippingCountry = 'USA';
        insert a;  
        
        Opportunity o = new Opportunity();
        o.Name = 'Telecom Potential Sale';
        o.AccountId = a.Id;
        o.salesReach__Agent_Account_Company_Name__c = a.salesReach__Agent_Account_Company_Name__c;
        o.salesReach__Agent_Contact_Name__c = a.salesReach__Agent_Contact_Name__c;
        o.CloseDate = date.today();
        o.StageName = 'Quote Requested By Client';
        o.Opportunity_Type__c = 'Renew Existing Service';
        o.Opportunity_Contact__c = '003a0000028fI7L';
        insert o;
        
        Quote q = new Quote();
        q.Name = 'Telecom Potential Sale - Quote';
        q.ExpirationDate = o.Quote_Expiration_Date__c;
        q.ContactId = o.Opportunity_Contact__c;
        q.Status = 'Draft';
        q.OpportunityId = o.Id;
        insert q;
        
        q.Status = 'Accepted';
        update q;
        
    }

}


Can someone please help me fix this?  Thank you!