Deleting Apps/Repos: App matching query does not exist.

Sometimes, when deleting an app or a repo, Repomaker fails with the error App matching query does not exist. This is because Repomaker tries to delete an app icon in a post delete apk pointer handler but the app does not exist anymore.

@grote You therefore included the check if self.app: but curiously this is exactly the point where it fails. I couldn't come up with a fix. As a workaround, I'm removing the check to be able to delete apps and repos.

Git blame of the affected line: https://gitlab.com/fdroid/repomaker/blame/master/repomaker/models/apkpointer.py#L133

Environment:


Request Method: POST
Request URL: http://127.0.0.1:8000/4/app/10/delete/

Django Version: 1.11.4
Python Version: 3.5.4
Installed Applications:
['repomaker.apps.RepoMakerConfig',
 'sass_processor',
 'background_task',
 'hvad',
 'tinymce',
 'django_js_reverse',
 'django.forms',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'django.contrib.sites',
 'allauth.account']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/fields/related_descriptors.py" in __get__
  178.             rel_obj = getattr(instance, self.cache_name)

During handling of the above exception ('ApkPointer' object has no attribute '_app_cache'), another exception occurred:

File "/home/dev/.local/lib/python3.5/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/home/dev/.local/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/home/dev/.local/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/home/dev/Work/F-Droid/repomaker/repomaker/views/__init__.py" in dispatch
  217.             return super().dispatch(request, *args, **kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/contrib/auth/mixins.py" in dispatch
  56.         return super(LoginRequiredMixin, self).dispatch(request, *args, **kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/contrib/auth/mixins.py" in dispatch
  116.         return super(UserPassesTestMixin, self).dispatch(request, *args, **kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/views/generic/edit.py" in post
  269.         return self.delete(request, *args, **kwargs)

File "/home/dev/.local/lib/python3.5/site-packages/django/views/generic/edit.py" in delete
  264.         self.object.delete()

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/base.py" in delete
  973.         return collector.delete()

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/deletion.py" in delete
  308.                             sender=model, instance=obj, using=self.using

File "/home/dev/.local/lib/python3.5/site-packages/django/dispatch/dispatcher.py" in send
  193.             for receiver in self._live_receivers(sender)

File "/home/dev/.local/lib/python3.5/site-packages/django/dispatch/dispatcher.py" in <listcomp>
  193.             for receiver in self._live_receivers(sender)

File "/home/dev/Work/F-Droid/repomaker/repomaker/models/apkpointer.py" in apk_pointer_post_delete_handler
  163.             apk_pointer.delete_app_icons_from_repo()

File "/home/dev/Work/F-Droid/repomaker/repomaker/models/apkpointer.py" in delete_app_icons_from_repo
  133.             if self.app:

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/fields/related_descriptors.py" in __get__
  184.                 rel_obj = self.get_object(instance)

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/fields/related_descriptors.py" in get_object
  159.         return qs.get(self.field.get_reverse_related_filter(instance))

File "/home/dev/.local/lib/python3.5/site-packages/django/db/models/query.py" in get
  380.                 self.model._meta.object_name

Exception Type: DoesNotExist at /4/app/10/delete/
Exception Value: App matching query does not exist.