[Fixed][Bug][Editor] Mouse zooming outside bottom/right boundary causes error

[IchoTolot]

Reproducing:

- Open the editor.

- Try to mousewheel zoom by while the mouse itself is outside the level boundaries on the bottom or right side (left and top outside boundaries seem to be ok).
   Note: This has to be the first mousewheel zoom you do since opening the editor. When you had 1 successful zoom before, the error doesn't occur anymore.

- Get a nice error message that implies the program tried to devide by zero. All future zooms will cause the same error now.

[Nepster]

Weirdly enough, this is exactly the same debugging statement that cause the exception on changing the level size.