[FIX] *: reports: check required values for 'render_html'

Some reports require additional information to render. When
accessed in Odoo, the user has to fill a wizard to provide those
information. However, when these reports were opened in Studio,
it crashed as those information were missing (we don't pass
through the configuration wizard in this case).

This fix checks if all the required information are given before
trying to render those reports, and it displays a warning in
the logs in they are missing, which is better than a traceback.