Homey fanspeed insights

[Mexxwelll]

Describe the bug
I use Homey to control the ithowifi device, and want to add the fanspeed Insights. But i receive the following error: Cannot assign to read only property 'topics' of object '#

To Reproduce
Steps to reproduce the behaviour:

1. Go to 'Homey'
2. Click on 'Ihto device'
3. Scroll down to 'Topics'

{
"dim": {
"capability": "dim",
"stateTopic": "homie/homey/mechanische-ventilatie/state",
"setTopic": "homie/homey/mechanische-ventilatie/cmd",
"valueTemplate": "round((value / 255) * 100)",
"outputTemplate": "round((value / 100) * 255)",
"displayName": "Dim level"
},
"measure_temperature": {
"capability": "measure_temperature",
"stateTopic": "homie/homey/mechanische-ventilatie/ithostatus",
"setTopic": "",
"valueTemplate": "$['temp']",
"outputTemplate": "",
"displayName": "Temperature"
},
"measure_humidity": {
"capability": "measure_humidity",
"stateTopic": "homie/homey/mechanische-ventilatie/ithostatus",
"setTopic": "",
"valueTemplate": "$['hum']",
"outputTemplate": "",
"displayName": "Humidity"
},
"measure_fanspeed": {
"capability": "measure_fanspeed",
"stateTopic": "homie/homey/mechanische-ventilatie/ithostatus",
"setTopic": "",
"valueTemplate": "$['Fan speed (rpm)']",
"outputTemplate": "",
"displayName": "Fanspeed"
}
}

4. See error: Cannot assign to read only property 'topics' of object '#

This config is working fine:
{
"dim": {
"capability": "dim",
"stateTopic": "homie/homey/mechanische-ventilatie/state",
"setTopic": "homie/homey/mechanische-ventilatie/cmd",
"valueTemplate": "round((value / 255) * 100)",
"outputTemplate": "round((value / 100) * 255)",
"displayName": "Dim level"
},
"measure_temperature": {
"capability": "measure_temperature",
"stateTopic": "homie/homey/mechanische-ventilatie/ithostatus",
"setTopic": "",
"valueTemplate": "$['temp']",
"outputTemplate": "",
"displayName": "Temperature"
},
"measure_humidity": {
"capability": "measure_humidity",
"stateTopic": "homie/homey/mechanische-ventilatie/ithostatus",
"setTopic": "",
"valueTemplate": "$['hum']",
"outputTemplate": "",
"displayName": "Humidity"
}
}

[arjenhiemstra]

is Fan speed (rpm) available on the mentioned MQTT topic?