- fix polyobject init

src/maploader/polyobjects.cpp

@@ -352,6 +352,7 @@ void MapLoader::PO_Init (void)
 	InitSideLists ();
 
 	Level->Polyobjects.Resize(NumPolyobjs);
+	for (auto &po : Level->Polyobjects) po.Level = Level;	// must be done before the init loop below.
 
 	polyIndex = 0; // index polyobj number
 	// Find the startSpot points, and spawn each polyobj

src/p_maputl.h

@@ -312,8 +312,9 @@ class FBlockThingsIterator
 
 public:
 	FBlockThingsIterator(FLevelLocals *Level, int minx, int miny, int maxx, int maxy);
-	FBlockThingsIterator(FLevelLocals *Level, const FBoundingBox &box)
+	FBlockThingsIterator(FLevelLocals *l, const FBoundingBox &box)
 	{
+		Level = l;
 		init(box);
 	}
 	void init(const FBoundingBox &box);