django-nonrel/mongodb-engine — comment on commit 0608fc1d7bb413ba42df4a731c8e00d8327a5dc2
File:  line 0
By jonashaag:

We need to be *100%* sure no exception is raised in the compiler except `DatabaseError`, because all other exceptions are "swallowed" by the `list(...)` call in `django.db.models.query.QuerySet.__len__:80` and then this happens

```pycon
>>> Foo.objects.filter(...) # throws some exception
[]
```