Ensure ScreenEvent doesn't accept null screens (#8296)

src/main/java/net/minecraftforge/client/event/ScreenEvent.java

@@ -21,6 +21,7 @@ package net.minecraftforge.client.event;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.function.Consumer;
 
 import com.mojang.blaze3d.vertex.PoseStack;
@@ -47,7 +48,7 @@ public class ScreenEvent extends Event
 
     public ScreenEvent(Screen screen)
     {
-        this.screen = screen;
+        this.screen = Objects.requireNonNull(screen);
     }
 
     /**