Don't set invalid zoom level when no previous texture size is set
Don't set invalid zoom level when no previous texture size is set

TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,googlestadia/renderdoc,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,googlestadia/renderdoc,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,baldurk/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,Zorro666/renderdoc,Zorro666/renderdoc,baldurk/renderdoc