app should never return empty fields with {{template}}

Nobody has claimed this yet.

I have to pepper my code with lots of bits like and similar to this to check for empty user fields. makes things more complex that they have to be.

jasonette should return empty fields and not let code percolate to the back-end app.

```ruby
check = [@event.title, @event.password, @event.host].map{|s| s =~ /{{/ }.compact
if check.size > 0
# some of the elements have "{{$get.xxx_yyy}}" in them, means they are empty!
render json: {}, status: :unprocessable_entity
return
end
```

No file or test is named. Start by reproducing a template containing empty user fields and trace where those fields are handled before reaching the backend; done means empty fields are handled by the app without requiring callers to add checks like the example.

Written by the indexing model from the issue text.