exception should be handled properly

Environment:


Request Method: POST
Request URL: http://pdp-test.lcsb.uni.lu/mail_templates/1/delete

Django Version: 1.11.5
Python Version: 2.7.12
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django_cleanup',
 'django_cron',
 'django_otp',
 'django_otp.plugins.otp_static',
 'django_otp.plugins.otp_totp',
 'two_factor',
 'web',
 'stronghold',
 'debug_toolbar']
Installed Middleware:
['debug_toolbar.middleware.DebugToolbarMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django_otp.middleware.OTPMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'stronghold.middleware.LoginRequiredMiddleware']



Traceback:

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/var/www/scheduling-system/smash/web/views/__init__.py" in dispatch
  79.         return super(WrappedView, self).dispatch(*args, **kwargs)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/views/generic/edit.py" in post
  269.         return self.delete(request, *args, **kwargs)

File "/var/www/scheduling-system/smash/web/views/mails.py" in delete
  79.         return super(MailTemplatesDeleteView, self).delete(request, *args, **kwargs)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/views/generic/edit.py" in delete
  264.         self.object.delete()

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/models/base.py" in delete
  973.         return collector.delete()

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/models/deletion.py" in delete
  308.                             sender=model, instance=obj, using=self.using

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/transaction.py" in __exit__
  267.                     connection.set_autocommit(True)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/backends/base/base.py" in set_autocommit
  416.             self.run_and_clear_commit_hooks()

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/backends/base/base.py" in run_and_clear_commit_hooks
  651.             func()

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django_cleanup/handlers.py" in run_on_commit
  92.         file_.delete(save=False)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/db/models/fields/files.py" in delete
  112.         self.storage.delete(self.name)

File "/var/www/scheduling-system/env/local/lib/python2.7/site-packages/django/core/files/storage.py" in delete
  386.             os.remove(name)

Exception Type: OSError at /mail_templates/1/delete
Exception Value: [Errno 13] Permission denied: '/var/www/scheduling-system-files/media/upcoming_appointment_FR.docx'