IndexError: index 804 is out of bounds for axis 0 with size 800

i installed a self driving car project from superdatascience site , when i open the map using terminal after a while the map window close up or it closes directly after i maximize the map window and it gives me this error :

    [INFO   ] [Base        ] Leaving application in progress...
 Traceback (most recent call last):
   File "map.py", line 235, in <module>
     CarApp().run()
   File "/usr/lib/python2.7/dist-packages/kivy/app.py", line 826, in run
     runTouchApp()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 502, in runTouchApp
     EventLoop.window.mainloop()
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/window_sdl2.py", line 727, in mainloop
     self._mainloop()
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/window_sdl2.py", line 460, in _mainloop
     EventLoop.idle()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 340, in idle
     self.dispatch_input()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 325, in dispatch_input
     post_dispatch_input(*pop(0))
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 231, in post_dispatch_input
     listener.dispatch('on_motion', etype, me)
   File "kivy/_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/__init__.py", line 1360, in on_motion
     self.dispatch('on_touch_down', me)
   File "kivy/_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/__init__.py", line 1376, in on_touch_down
     if w.dispatch('on_touch_down', touch):
   File "kivy/_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
   File "/usr/lib/python2.7/dist-packages/kivy/uix/widget.py", line 460, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy/_event.pyx", line 707, in kivy._event.EventDispatcher.dispatch
   File "map.py", line 181, in on_touch_down
     sand[int(touch.x),int(touch.y)] = 1
 IndexError: index 620 is out of bounds for axis 1 with size 600

the code i have in the brain ( ai.py file ) is

    class Dqn():

    def select_action(self, state):
            probs = F.softmax(self.model(Variable(state, volatile = True))*100) # T=100
        action = probs.multinomial(num_samples=1)
            return action.data[0,0]

the code i have in the map ( map.py file ) is

class MyPaintWidget(Widget):

    def on_touch_down(self, touch):
        global length, n_points, last_x, last_y
        with self.canvas:
            Color(0.8,0.7,0)
            d = 10.
            touch.ud['line'] = Line(points = (touch.x, touch.y), width = 10)
            last_x = int(touch.x)
            last_y = int(touch.y)
            n_points = 0
            length = 0
            sand[int(touch.x),int(touch.y)] = 1

what should i do or change ??

def on_touch_down(self, touch)
...
...
    try:
        sand[int(touch.x), int(touch.y)] = 1
    except IndexError:
        print("Touchdown did not occur within the end-zone! No goal!")