Currently Occurrence#_feedback methods return an instance of
BatchLoader which mimics almost all the behaviour of proxied object
but it's not perfect.
We can't use safe navigation operator on these return objects because
they are not actually `nil` since the Ruby VM just checks the object to
see if it's `NIL_P` before sending the message.
This causes getting NoMethodError on nil:NilClass which causes tears
on developers' eye.

Here we are explicitly returning an instance of Feedback model and also
loading all the feedback of all occurrences which solves the hidden
N+1 query issue.