Turtle library in python gives 'terminator' problems

I am having problems with the following code although it is very simple. The error has to do with the python turtle library, and I've been fighting for a few days. When I run the code for the first time, it works. But when I close the window of the turtle popup and run the code again, an error appears and I have to restart the kernel so that it works again. I attach the code:

import turtle as t
def draw_chart():
  alex = t.Turtle()
  alex.fd(50)

window = t.Screen()
window.bgcolor('white')
window.setup(600,600)

draw_chart()

window.mainloop()

And I get the following error:

----------------------------------------------------------------------------
Terminator                                Traceback (most recent call last)
<ipython-input-4-c21753aaf0da> in <module>
      5 window.title('Buscaminas')
      6 
----> 7 draw_chart(window)
      8 
      9 window.mainloop()

<ipython-input-3-c74be4cddd4a> in draw_chart(finestra)
      1 import turtle as t
      2 def draw_chart(finestra):
----> 3     alex = t.Turtle()
      4     alex.st()
      5     alex.fd(50)

...\python\python37-32\lib\turtle.py in __init__(self, shape, undobuffersize, visible)
   3814                            shape=shape,
   3815                            undobuffersize=undobuffersize,
-> 3816                            visible=visible)
   3817 
   3818 Pen = Turtle

...\python\python37-32\lib\turtle.py in __init__(self, canvas, shape, undobuffersize, visible)
   2555         self._undobuffersize = undobuffersize
   2556         self.undobuffer = Tbuffer(undobuffersize)
-> 2557         self._update()
   2558 
   2559     def reset(self):

...\python\python37-32\lib\turtle.py in _update(self)
   2658             return
   2659         elif screen._tracing == 1:
-> 2660             self._update_data()
   2661             self._drawturtle()
   2662             screen._update()                  # TurtleScreenBase

...\python\python37-32\lib\turtle.py in _update_data(self)
   2644 
   2645     def _update_data(self):
-> 2646         self.screen._incrementudc()
   2647         if self.screen._updatecounter != 0:
   2648             return

...\python\python37-32\lib\turtle.py in _incrementudc(self)
   1290         if not TurtleScreen._RUNNING:
   1291             TurtleScreen._RUNNING = True
-> 1292             raise Terminator
   1293         if self._tracing > 0:
   1294             self._updatecounter += 1

Terminator: 

Thank you very much in advance.