'Determine if error should be handled with FR or default Flask
The goal is to return Flask error handlers for non-FR-related routes,
and FR errors (with the correct media type) for FR endpoints. This
method currently handles 404 and 405 errors.
:return: bool'

def _should_use_fr_error_handler(self):

    adapter = current_app.create_url_adapter(request)
    try:
        adapter.match()
    except MethodNotAllowed as e:
        valid_route_method = e.valid_methods[0]
        (rule, _) = adapter.match(method=valid_route_method, return_rule=True)
        return self.owns_endpoint(rule.endpoint)
    except NotFound:
        return self.catch_all_404s
    except:
        pass
