# Buggy code
def _handle_event(self, event):
    """Handle events.

    This will update PUSH_NOTIFICATION_CHANGE events to see if the sensor
    should be updated.
    """
    try:
        if not self.enabled:
            return
    except AttributeError:
        pass
    if "notification_update" in event.data:
        if (
            event.data["notification_update"]["dopplerId"]["deviceSerialNumber"]
            == self._client.unique_id
        ):
            _LOGGER.debug("Updating sensor %s", self.name)
            self.async_schedule_update_ha_state(True)


# Traceback (ValueError)
2019-10-26 14:43:05 ERROR (MainThread) [homeassistant.config_entries] Error setting up entry ***REDACTED*** - amazon.com for media_player
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/config_entries.py", line 190, in async_setup
hass, self
File "/usr/src/homeassistant/homeassistant/components/media_player/__init__.py", line 340, in async_setup_entry
return await hass.data[DOMAIN].async_setup_entry(entry)
File "/usr/src/homeassistant/homeassistant/helpers/entity_component.py", line 151, in async_setup_entry
raise ValueError("Config entry has already been setup!")
ValueError: Config entry has already been setup!
2019-10-26 14:43:05 ERROR (MainThread) [homeassistant.config_entries] Error setting up entry ***REDACTED*** - amazon.com for alarm_control_panel
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/config_entries.py", line 190, in async_setup
hass, self
File "/usr/src/homeassistant/homeassistant/components/alarm_control_panel/__init__.py", line 74, in async_setup_entry
return await hass.data[DOMAIN].async_setup_entry(entry)
File "/usr/src/homeassistant/homeassistant/helpers/entity_component.py", line 151, in async_setup_entry
raise ValueError("Config entry has already been setup!")
ValueError: Config entry has already been setup!
2019-10-26 14:43:05 ERROR (MainThread) [homeassistant.config_entries] Error setting up entry ***REDACTED*** - amazon.com for switch
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/config_entries.py", line 190, in async_setup
hass, self
File "/usr/src/homeassistant/homeassistant/components/switch/__init__.py", line 79, in async_setup_entry
return await hass.data[DOMAIN].async_setup_entry(entry)
File "/usr/src/homeassistant/homeassistant/helpers/entity_component.py", line 151, in async_setup_entry
raise ValueError("Config entry has already been setup!")
ValueError: Config entry has already been setup!
2019-10-26 14:43:05 ERROR (MainThread) [homeassistant.config_entries] Error setting up entry ***REDACTED*** - amazon.com for sensor
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/config_entries.py", line 190, in async_setup
hass, self
File "/usr/src/homeassistant/homeassistant/components/sensor/__init__.py", line 60, in async_setup_entry
return await hass.data[DOMAIN].async_setup_entry(entry)
File "/usr/src/homeassistant/homeassistant/helpers/entity_component.py", line 151, in async_setup_entry
raise ValueError("Config entry has already been setup!")
ValueError: Config entry has already been setup!**System details**```

# Fixed code
def _handle_event(self, event):
    """Handle events.

    This will update PUSH_NOTIFICATION_CHANGE events to see if the sensor
    should be updated.
    """
    try:
        if not self.enabled:
            return
    except AttributeError:
        pass
    if "notification_update" in event:
        if (
            event["notification_update"]["dopplerId"]["deviceSerialNumber"]
            == self._client.unique_id
        ):
            _LOGGER.debug("Updating sensor %s", self.name)
            self.async_schedule_update_ha_state(True)