- Fixed crash exiting from the iwad selector.

src/d_main.cpp

@@ -1010,6 +1010,7 @@ void D_Display ()
 void D_ErrorCleanup ()
 {
 	savegamerestore = false;
+	if (screen)
 		screen->Unlock ();
 	bglobal.RemoveAllBots (true);
 	D_QuitNetGame ();

src/p_setup.cpp

@@ -3151,6 +3151,7 @@ void P_FreeLevelData ()
 	AActor::ClearTIDHashes();
 
 	interpolator.ClearInterpolations();	// [RH] Nothing to interpolate on a fresh level.
+	if (Renderer)
 		Renderer->CleanLevelData();
 	FPolyObj::ClearAllSubsectorLinks(); // can't be done as part of the polyobj deletion process.
 	SN_StopAllSequences ();