Thanks for the suggestion. I am running v2.4.1.177
I still got the same error
errorgroovy.lang.MissingMethodException: No signature of method: user_driver_SeriesOfUnlikelyExplanations_Daikin_OnePlus_Single_Thermostat_1567.setSupportedThermostatFanModes() is applicable for argument types: (java.lang.String) values: [["auto","on"]] on line 83 (method installed)
Just to confirm I interpreted your requested edits to line 83 & 84 as follows:
def initialize(){
setSupportedThermostatFanModes(JsonOutput.toJson(["auto","on"]))
setSupportedThermostatModes(JsonOutput.toJson(["heat","cool","auto","off"]))
}