It's the same, unfortunately. I looked at the gifs you put up as tutorials, which show an editing area with a grey background. Unless I'm mistaken, I should be getting that too, correct? Also, inputting a value into the new box does nothing, and I still get that exception.
Nope, there should be a pop-up asking you how wide and tall your new map is going to be.
The recording software I used somehow skipped the popup AND paused recording until I refocused on the editor. It's a mistake on my part but I really don't know how to work around that.
The pop-up should look like this:
EDIT:That error is now going to haunt me.
So, the pop-up appeared, and you input a value. After that, you pressed OK, and then it crashed? I really don't know how that works, especially when the log out suggested that the values received are 0, and 0 respectively. It's even more confusing when the fact that the editor crashed when it's creating the BufferStrategy, so that is indeed something weird.