Issue with AHUD function. Please Help

Hello

I am working on a C++ book (I have been around the forums a lot lately ,since this book is apparently really bad)

I am trying to create a function that will allow me to draw a backing color to a text box.

The errors I am getting are as follows

Here is the current code for MyHUD.c++ file

#include "MyHUD.h"
#include "CoreMinimal.h"

void AMyHUD::DrawHUD() 
{
	Super::DrawHUD();

	for (int c = messages.Num() - 1; c >= 0; c--)
	{
		// draw the background box the right size 
		// for the message 
		float outputWidth, outputHeight, pad = 10.f;
		GetTextSize(messages[c].message, outputWidth, outputHeight,
			hudFont, 1.f);

		float messageH = outputHeight + 2.f*pad;
		float x = 0.f, y = c * messageH;

		// black backing 
		DrawRect(FLinearColor::Black, x, y, Canvas->SizeX, messageH);
		// draw our message using the hudFont 
		DrawText(messages[c].message, messages[c].color, x + pad, y +
			pad, hudFont);

		// reduce lifetime by the time that passed since last  
		// frame. 
		messages[c].time -= GetWorld()->GetDeltaSeconds();

		// if the message's time is up, remove it 
		if (messages[c].time < 0)
		{
			messages.RemoveAt(c);
		}

	}
}

void AMyHUD::addMessage(Message msg)
{
	messages.Add(msg);
}

I hate to ask for help, but this book is really bad (Like the downloaded source code often does not work).
Thank you for your time.

The image is the error log,
Sorry if that’s out of the way.