Hotend fan temperature control

Greetings!

Before upgrading to RatOS I used to ensure my hotend fan would only spin over a certain temperature by using the following:

[heater_fan t0hotend_fan]
pin: toolboard_t0:fan_part_cooling_pin (Previously a different pin)
heater: extruder
heater_temp: 50

If I insert this in my printer.cfg, I get the error shown in the picture.
Any help is greatly appreciated!