not sure what these updates are

map.json

@@ -83,9 +83,10 @@
     "Farm Region": [-235, 80, -100, true, {"radius": 230, "color": [0, 0.5, 0, 0.15], "offset": [-54, 0]}],
     "Mount Sharpe": [735, 110, 685, "mountainous region", {"radius": 165, "color": [1, 1, 1, 0.1], "offset": [-54, 4]}],
     "approximate area of extreme mountains": [-50, 100, 750, true, {"radius": [570, 525], "color": [1, 1, 1, 0.15]}],
-    "map_3": [448, 64, 448, false, {"image": "images/map_3.png", "size": [1024, 1024], "color": [1, 1, 1, 0.5]}],
+    "map_3": [448, 64, 448, true, {"image": "images/map_3.png", "size": [1024, 1024], "color": [1, 1, 1, 0.33]}],
     "unnamed hill": [400, 100, 235, true, {"radius": [110, 100], "offset": [-40, 0]}],
     "unnamed plains": [40, 100, 140, true, {"radius": [115, 85], "offset": [-50, 0]}],
-    "original worldborder": [0, 87, 0, false, {"box": [1000, 1000], "mode": "line"}]
+    "original worldborder": [0, 87, 0, false, {"box": [1000, 1000], "mode": "line"}],
+    "possible runway location": [-40, 100, 135, null, {"box": [64, 9], "mode": "line"}]
   }
 }

src/main.lua

@@ -33,6 +33,7 @@ local function load_map(map_file_name)
     file:open("r")
     text = file:read("string")
   end
+  file:close()
 
   local map = json.decode(text)
   nodes = map.nodes or {}