Fix level loading and add an empty level.

main.py

@@ -43,9 +43,10 @@ def mainLoop():
     wall_buffer = []
     
     try:
-        level = parse_level_from_string(open_level(sys.argv[1]))
+        leveltoparse = open_level(sys.argv[1])
     except IndexError:
-        level = parse_level_from_string(open_level("maps/cuberoom.p3hel"))
+        leveltoparse = open_level("maps/cuberoom.p3hel")
+    level = parse_level_from_string(leveltoparse)
 
     while True:
         for event in pygame.event.get():

maps/empty.p3hel

@@ -0,0 +1 @@
+True/0/0/(0, 0, 0