Fix bug when trying to read states of MQTT light when it is off.

[pszafer]

Description:

This week I started to using RGB MQTT light and found a bug in mqtt light implementation.
When I call to turn off light, it tried to read rgb state when light is already off.
It occurs if state topic and brightness/color topic etc. are the same.

Exception thrown:

2018-12-11 15:15:07 ERROR (MainThread) [homeassistant.helpers.template] Error parsing value: 'dict object' has no attribute 'Color' (value: {"POWER":"OFF"}, template: {{value_json.Color.split(',')[0:3]|join(',')}})                                                         
2018-12-11 15:15:07 ERROR (MainThread) [homeassistant.core] Error doing job: Exception in callback MQTT._mqtt_handle_message(<paho.mqtt.cl...x7fb43fb67dd8>)                                                                                                                   
Traceback (most recent call last):
  File "/usr/lib/python3.6/asyncio/events.py", line 145, in _run
    self._callback(*self._args)
  File "/root/homeassistant/lib/python3.6/site-packages/homeassistant/components/mqtt/__init__.py", line 775, in _mqtt_handle_message
    subscription.callback, msg.topic, payload, msg.qos)
  File "/root/homeassistant/lib/python3.6/site-packages/homeassistant/core.py", line 327, in async_run_job
    target(*args)
  File "/root/homeassistant/lib/python3.6/site-packages/homeassistant/components/light/mqtt.py", line 331, in rgb_received
    rgb = [int(val) for val in payload.split(',')]
  File "/root/homeassistant/lib/python3.6/site-packages/homeassistant/components/light/mqtt.py", line 331, in <listcomp>
    rgb = [int(val) for val in payload.split(',')]
ValueError: invalid literal for int() with base 10: '{"POWER":"OFF"}'

**Related issue (if applicable): couldn't find any.

Example entry for configuration.yaml (if applicable):

Config which threw error:

- platform: mqtt
  name: "LED light"
  command_topic: "cmnd/led/POWER"
  state_topic: "stat/led/RESULT"
  state_value_template: "{{value_json.POWER}}"
  availability_topic: "tele/led/LWT"
  brightness_command_topic: "cmnd/led/Dimmer"
  brightness_state_topic: "stat/led/RESULT"
  brightness_scale: 100
  on_command_type: "brightness"
  brightness_value_template: "{{value_json.Dimmer}}"
  color_temp_command_topic: "cmnd/led/CT"
  color_temp_state_topic: "stat/led/RESULT"
  color_temp_value_template: "{{value_json.CT}}"
  rgb_command_topic: "cmnd/led/Color2"
  rgb_state_topic: "stat/led/RESULT"
  rgb_value_template: "{{value_json.Color.split(',')[0:3]|join(',')}}"
  effect_command_topic: "cmnd/led/Scheme"
  effect_state_topic: "stat/led/RESULT"
  effect_value_template: "{{value_json.Scheme}}"
  effect_list:
    - 0
    - 1
    - 2
    - 3
    - 4
  payload_on: "ON"
  payload_off: "OFF"
  payload_available: "Online"
  payload_not_available: "Offline"

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• Tests have been changed to verify that the new code works.

[emontnemery]

This is not a bug in Hass, and has been fixed in Tasmota.

However, Tasmota documentation has not been updated yet.

Please open an issue on Tasmota and ping me.