There was a nullptr error happened in the code

I got a nullptr error in Unreal Engine 4. I tried to attach HealthComponent but I failed.

Exception: read access violation. this->HealthComponent was nullptr.

What should I do to fix it?

STUBaseCharacter.h

#include "CoreMinimal.h"
#include "GameFramework/Character.h"
#include "STUBaseCharacter.generated.h"

class UCameraComponent;
class USTUHealthComponent;
class USpringArmComponent;
class UTextRenderComponent;

UCLASS()
class SHOOTTHEMUP_API ASTUBaseCharacter : public ACharacter
{
    GENERATED_BODY()

  public:
    ASTUBaseCharacter(const FObjectInitializer &ObjInit);

  protected:

    UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Components")
    USTUHealthComponent *HealthComponent;

    UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Components")
    USpringArmComponent *SpringArmComponent;

    UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Components")
    UCameraComponent *CameraComponent;

STUBaseCharacter.cpp

#include "Player/STUBaseCharacter.h"
#include "Camera/CameraComponent.h"
#include "Components/InputComponent.h"
#include "Components/STUCharacterMovementComponent.h"
#include "Components/STUHealthComponent.h"
#include "Components/TextRenderComponent.h"
#include "GameFramework/Controller.h"
#include "GameFramework/SpringArmComponent.h"

DEFINE_LOG_CATEGORY_STATIC(LogBaseCharacter, All, All);

ASTUBaseCharacter::ASTUBaseCharacter(const FObjectInitializer &ObjInit)
    : Super(
          ObjInit.SetDefaultSubobjectClass<USTUCharacterMovementComponent>(ACharacter::CharacterMovementComponentName))
{
    PrimaryActorTick.bCanEverTick = true;

    SpringArmComponent = CreateDefaultSubobject<USpringArmComponent>("SpringArmComponent");
    SpringArmComponent->SetupAttachment(GetRootComponent());
    SpringArmComponent->bUsePawnControlRotation = true;

    CameraComponent = CreateDefaultSubobject<UCameraComponent>("CameraComponent");
    CameraComponent->SetupAttachment(SpringArmComponent);

    HealthComponent = CreateDefaultSubobject<USTUHealthComponent>("HealthComponent");

    HealthTextComponent = CreateDefaultSubobject<UTextRenderComponent>("HealthTextComponent");
    HealthTextComponent->SetupAttachment(GetRootComponent());
}

void ASTUBaseCharacter::BeginPlay()
{
    Super::BeginPlay();

    check(HealthComponent); // error
    check(HealthTextComponent);
    check(GetCharacterMovement());

    OnHealthChanged(HealthComponent->GetHealth());
    HealthComponent->OnDeath.AddUObject(this, &ASTUBaseCharacter::OnDeath);
    HealthComponent->OnHealthChanged.AddUObject(this, &ASTUBaseCharacter::OnHealthChanged);

    LandedDelegate.AddDynamic(this, &ASTUBaseCharacter::OnGroundLanded);
}

What is the problem here? If I delete these fields the project is working.

        check(HealthComponent); 
        OnHealthChanged(HealthComponent->GetHealth());
        HealthComponent->OnDeath.AddUObject(this, &ASTUBaseCharacter::OnDeath);
        HealthComponent->OnHealthChanged.AddUObject(this, &ASTUBaseCharacter::OnHealthChanged);

Also if I open BP_Character and I choose HealthComponent field there is nothing in the details place