Apex Test Class throwing NullPointerException

UPDATE

• NullPointerException error has been resolved (thanks @Adrian)
• INVALID_PERSON_ACCOUNT_OPERATION error was resolved by adding a RecTypeId variable
• Now I am confronted by an insert error: REQUIRED_FIELD_MISSING, Required fields are missing: [ContactId]: [ContactId] (stack trace is Class.lifeEventNotifyControllerTest.TestSOQL: line 24, column 1)

Since I am looking at the Person Account, dummyContact.Id isn't an option, so I tried dummyContact.PersonContactId but that threw the same error. What am I missing?

Updated Apex Test

@isTest
private class lifeEventNotifyControllerTest { 

    static testMethod void TestSOQL() {
        String loggedUserId = UserInfo.getUserId();
        String RecTypeId = [SELECT Id FROM RecordType WHERE (Name='Person Account') AND (SobjectType='Account')].Id;
        
        Account dummyContact = new Account();
        dummyContact.RecordTypeID = RecTypeId;
        dummyContact.Firstname = 'Test';
        dummyContact.Lastname = 'Contact';
        dummyContact.PersonBirthdate = date.today();
        dummyContact.Contact_Type__pc = 'Sponsor';
        INSERT dummyContact;

        Account dummyAcct = new Account();
        dummyAcct.Name = 'Test Company';
        dummyAcct.Custom__c = loggedUserId;
        INSERT dummyAcct;

        AccountContactRelation acr = new AccountContactRelation();
        acr.ContactId = dummyContact.PersonContactId;
        acr.AccountId = dummyAcct.Id;
        INSERT acr;

        lifeEventNotifyController testCont = new lifeEventNotifyController ();
        List<AccountContactRelation> dummyList = testCont.getLifeEvents();

        System.assert(dummyList  != null);
        
    }
}

Original Question:

I am brand new to Apex development and am learning about the importance of code coverage. Right now I have a very simple Apex class querying the AccountContactRelation object via SOQL. When trying to create an Apex test class, I continue to get the following error:

"System.NullPointerException: Attempt to de-reference a null object" error.

Browsing StackExchange I believe this error has to do with my Account and Contact objects not being initialized in the test class?

Apex Class

public with sharing class lifeEventNotifyController {
  @AuraEnabled
  public List<AccountContactRelation> getLifeEvents() {
    // get current user id
    String loggedUserId = UserInfo.getUserId();
    List<AccountContactRelation> lifeEventList = [SELECT Id, ContactId, Contact.Name, Contact.Birthdate, AccountId, Account.Name FROM AccountContactRelation WHERE Account.Custom__c = :loggedUserId AND (Contact.Days_to_Birthday__c <= 7 OR Contact.Days_to_Birthday__c = 365)];
    
    return lifeEventList;

  }
}

NOTE: In the above class, Days_to_Birthday__c is a formula field based on the Contact.Birthdate date field.

Apex Test Class

@isTest
private class lifeEventNotifyControllerTest { 

    static testMethod void TestSOQL() {
        String loggedUserId = UserInfo.getUserId();
        
        Contact dummyContact = new Contact();
        dummyContact.Firstname = 'Test';
        dummyContact.Lastname = 'Contact';
        dummyContact.Birthdate = date.today();
        INSERT dummyContact;

        Account dummyAcct = new Account();
        dummyAcct.Name = 'Test Company';
        dummyAcct.Custom__c = loggedUserId;
        INSERT dummyAcct;

        AccountContactRelation acr = new AccountContactRelation();
        acr.ContactId = dummyContact.Id;
        acr.Contact.Birthdate = dummyContact.Birthdate;
        acr.AccountId = dummyAcct.Id;
        acr.Account.Name = dummyAcct.Name;
        acr.Account.Custom__c = dummyAcct.Custom__c;
        INSERT acr;

        lifeEventNotifyController testCont = new lifeEventNotifyController ();
        List<AccountContactRelation> dummyList = testCont.getLifeEvents();

        System.assert(dummyList  != null);
        
    }
}