Fixed|Client|Renderer: Crash with Vanilla profile in multiplayer

Todo: This is a quick fix. It seems there is an underlying oversight
in the logic wrt multiplayer games (clmobjs, perhaps?) that should be
examined more carefully.

IssueID #1693

doomsday/client/src/render/r_things.cpp

@@ -445,7 +445,7 @@ void R_ProjectSprite(mobj_t *mo)
     }
 
     // Do we need to project a flare source too?
-    if(mo->lumIdx != Lumobj::NoIndex)
+    if(mo->lumIdx != Lumobj::NoIndex && haloMode > 0)
     {
         /// @todo mark this light source visible for LensFx
         try