ERROR Exception in async_discover

hi

not sure if this an home assistant error or an add on or me not understanding how to edit the devices file

i keep getting this in the HA log (and the device is no longer usable) whenever i add the lines

homeassistant:
    # transition in seconds
    light:
      transition: 2

into zigbeetomqtt devices

so the full device is

'0x0017880104dff529':
  friendly_name: '0x0017880104dff529'
  homeassistant:
    # transition in seconds
    light:
      transition: 2

2020-06-06 01:15:23 ERROR (MainThread) [homeassistant.util.logging] Exception in async_discover when dispatching ‘mqtt_discovery_new_light_mqtt’: ({‘brightness’: True, ‘schema’: ‘json’, ‘command_topic’: ‘zigbee2mqtt/0x0017880104dff529/set’, ‘brightness_scale’: 254, ‘state_topic’: ‘zigbee2mqtt/0x0017880104dff529’, ‘json_attributes_topic’: ‘zigbee2mqtt/0x0017880104dff529’, ‘name’: ‘0x0017880104dff529_light’, ‘unique_id’: ‘0x0017880104dff529_light_zigbee2mqtt’, ‘device’: {‘identifiers’: [‘zigbee2mqtt_0x0017880104dff529’], ‘name’: ‘0x0017880104dff529’, ‘sw_version’: ‘Zigbee2mqtt 1.13.1’, ‘model’: ‘Hue White Single bulb B22 (8718696449691)’, ‘manufacturer’: ‘Philips’}, ‘availability_topic’: ‘zigbee2mqtt/bridge/state’, ‘transition’: 2, ‘platform’: ‘mqtt’},)
Traceback (most recent call last):
File “/usr/src/homeassistant/homeassistant/components/mqtt/light/init.py”, line 52, in async_discover
config = PLATFORM_SCHEMA(discovery_payload)
File “/usr/local/lib/python3.7/site-packages/voluptuous/validators.py”, line 208, in call
return self._exec((Schema(val) for val in self.validators), v)
File “/usr/local/lib/python3.7/site-packages/voluptuous/validators.py”, line 287, in _exec
raise e if self.msg is None else AllInvalid(self.msg, path=path)
File “/usr/local/lib/python3.7/site-packages/voluptuous/validators.py”, line 283, in _exec
v = func(v)
File “/usr/local/lib/python3.7/site-packages/voluptuous/schema_builder.py”, line 272, in call
return self._compiled([], data)
File “/usr/local/lib/python3.7/site-packages/voluptuous/schema_builder.py”, line 817, in validate_callable
return schema(data)
File “/usr/src/homeassistant/homeassistant/components/mqtt/light/init.py”, line 30, in validate_mqtt_light
return schemasvalue[CONF_SCHEMA]
File “/usr/local/lib/python3.7/site-packages/voluptuous/schema_builder.py”, line 272, in call
return self._compiled([], data)
File “/usr/local/lib/python3.7/site-packages/voluptuous/schema_builder.py”, line 594, in validate_dict
return base_validate(path, iteritems(data), out)
File “/usr/local/lib/python3.7/site-packages/voluptuous/schema_builder.py”, line 432, in validate_mapping
raise er.MultipleInvalid(errors)
voluptuous.error.MultipleInvalid: extra keys not allowed @ data[‘transition’]