Wrapper around the ASGI callable, handling exceptions and unexpected
        termination states.

async def run_asgi(self):
        """
        Wrapper around the ASGI callable, handling exceptions and unexpected
        termination states.
        """
        try:
            result = await self.app(self.scope, self.asgi_receive, self.asgi_send)
        except BaseException as exc:
            self.closed_event.set()
            msg = "Exception in ASGI application\n"
            self.logger.error(msg, exc_info=exc)
            if not self.handshake_started_event.is_set():
                self.send_500_response()
            else:
                await self.handshake_completed_event.wait()
            self.transport.close()
        else:
            self.closed_event.set()
            if not self.handshake_started_event.is_set():
                msg = "ASGI callable returned without sending handshake."
                self.logger.error(msg)
                self.send_500_response()
                self.transport.close()
            elif result is not None:
                msg = "ASGI callable should return None, but returned '%s'."
                self.logger.error(msg, result)
                await self.handshake_completed_event.wait()
                self.transport.close()