Python error when playing music with Pyglet: UserWarning: exception: access violation reading 0x00000014

I tried several iterations of this code using methods, schedules and others. I managed to get over "access violation writing error" but "access violation reading error" is still present no matter what I try. Here is the code:

import pyglet

window = pyglet.window.Window()
window.set_caption('First Pyglet Experiment')

player = pyglet.media.Player()
player.queue(pyglet.resource.media('test song.mp3'))
player.loop = True

@window.event
def on_close():
    player.delete()

player.play()  
pyglet.app.run()  

After the first interaction of my song is done, it raises over and over this error:

D:\_Programming_\Python\venv\lib\site-packages\pyglet\media\codecs\wmf.py:771: UserWarning: exception: access violation reading 0x00000014
  warnings.warn(e)

I would appreciate any advice. Thanks in advance.

Ok, so everything solved itself when I used .wav instead of .mp3. It seems that pyglet supports mp3 but has some kind of internal problem with it. It could as well just be an incorrectly exported file.

You still need this part though:

@window.event
def on_close():
    player.delete()

this insured correct closing of the file if the window was suddenly closed. "access violation writing" error is still present without it.

For some reason this error is not present in this simple version:

import pyglet

window = pyglet.window.Window()
window.set_caption('First Pyglet Experiment')

music = pyglet.resource.media('background.wav')
music.play()

pyglet.app.run()

But causes problems in my more complex application. Probably the Player() needs to be turned off safely.