bugfix: [#34220] Blenderplayer no longer working after r54395 commit [segfault due to world not valid]
patch by Sergey Sharybin

note, I still find strange that world was valid and now it is not, but at least we no longer segfaults

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54538 954f8c5b-7b00-dc11-b283-0030488c597c