I accidentally clicked an "x" on something in a Game Mode Blueprint and now nothing shows up inside. How do I fix it and what happened?

I accidentally clicked an x on something in a Game Mode Blueprint and now nothing shows up inside. How do I fix it and what happened?

You’ve closed the ‘Class Defaults’ tab. I’ve done that once or twice too. You should be able to find it under Windows > Class Defaults. (this image is from UE5 but it should be the same in UE4)

image