"System.NullPointerException: Attempt to de-reference a null object" when deploying controller + test class

Question

I am trying to learn development while building Apex classes. I got this error upon trying to deploy a custom controller and test class from sandbox to production: "System.NullPointerException: Attempt to de-reference a null object"

Here is my controller:

public class MyController {

public final Contact c;
ApexPages.StandardController sc;
MyController m;
public MyController(ApexPages.StandardController sc) {
    this.c = (Contact)sc.getRecord();
}

public void quicksave() {
    Job_Applicant__c j = (Job_Applicant__c) sc.getRecord();
    update j.Contact_Candidate__r;
}
}

Here is my test class for the controller:

@isTest
public class testMyController{
public static testMethod void testMyController() {

    Contact c = new Contact(LastName = 'testmycontroller');
    insert c;
    
    Job_Applicant__c j = new Job_Applicant__c(Contact_Candidate__c = c.id);
    insert j;
    
        ApexPages.StandardController sc = new ApexPages.standardController(c);
    MyController m = new MyController(sc);
    System.assertEquals(m.c, c);
    
    Test.startTest();
    m.quicksave();
    test.stopTest();
}
}

Error msg:

Thank you

Answer 1

The member variable sc was never populated so is null when it is used in quickSave(). Simply populate it in the constuctor:

public MyController(ApexPages.StandardController sc) {
    this.c = (Contact)sc.getRecord();
    this.sc = sc;
}

Answer 2

Looks like the issue was in the test class, ultimately. Change set deployment was successful when I used this test class:

@isTest
public class testMyExtension{

    testmethod static void testcondition0(){
        test.startTest();
        try{
            Contact c = new Contact(LastName = 'test');
            insert c;
    
             AVTRRT__Job_Applicant__c j = new AVTRRT__Job_Applicant__c(AVTRRT__Contact_Candidate__c = c.id);
              insert j;
    
            j.AVTRRT__Contact_Candidate__c = c.id;
    
         ApexPages.StandardController sc = new ApexPages.standardController(j);
            MyExtension m = new MyExtension(sc);
            m.saveRecord();
        } catch (Exception e)
        {
            system.assert(e!=null);
        }
        test.stopTest();
    }
    
    
}

Thanks to all that made an effort to help.