I have this error, yet the game works and that variable ActorThatOpens get assigned correctly.
In my header the includes are:
#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "Engine/TriggerVolume.h"
#include "OpenDoor.generated.h"
As far as I can tell from the docs Components/ActorComponent.h contains the function GetWorld().
I have to go work now, but been scratching my head over this for an hour or so, and will continue to when i get home later. If anyone can see what I am doing wrong and can help I will be so grateful.
(As you can probably tell I am completely new to C++) THANKS!