I'm trying to deploy something like this: 

public class Send {
    
    public Send(){ 
    }

    public static Messaging.SingleEmailMessage createEmail(
                         String SenderName, Id TemplateId, Id ObjectId, Id WhatId) 
    {
        Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
        email.setTargetObjectId(ObjectId);
        email.setTemplateId(TemplateId);
        email.setWhatId(WhatId);
        email.setSenderDisplayName(SenderName);
        return email;
    }
    
    public static void MessageSent() {
        
        /* Create a list of email objects */
        Messaging.SingleEmailMessage [] emails = new Messaging.SingleEmailMessage[]{};
            
       /* Get a list of contacts */
        List<Contact> c = [SELECT Name, Id, AccountId
                           FROM Contact
                           WHERE Email != null AND Email != '' ];

        /* Find the size of all the contacts */
        Integer ContactSize = c.size();
        
        /* Locate the email template being used */
        EmailTemplate et = [SELECT id
                                    FROM EmailTemplate
                                    WHERE Name = 'CAF VF'];

/* Iterate through the list of contacts and send email to each */
        for (Integer i = 0; i < ContactSize; i++){
                
                Messaging.SingleEmailMessage temp = createEmail('Report', et.id, c[i].Id, c[i].AccountId);
                emails.add(temp);
            }
        
            try{
                Messaging.sendEmail(emails);
            } catch (Exception e) {
                System.debug('The following exception has occured: ' + e.getMessage());
            }         
    }
}

I get the following errors: 
 - System.NullPointerException: Attempt to de-reference a null object, Stack Trace: Class.MassUpdateSimpleControllerTest.testOpportunityInRelatedList: line 148, column 1
- System.AssertException: Assertion Failed, Stack Trace: Class.Milestone1_GettingStartedController.testGettingStartedProject: line 239, column 1
- System.NullPointerException: Attempt to de-reference a null object, Stack Trace: Class.Milestone1_GettingStartedController.getInitialSettingsWithoutSave: line 190, column 1 Class.Milestone1_GettingStartedController.testGetSettings: line 211, column 1

I have no idea how to fix this. Help me, please!