Nibeheatpump binding: exception when reading newly added register

Hi,

I need some help to add a register to the nibeheatpump binding. I have a Nibe heat pump with the passive cooling module (F1155PC). There is an undocumented register (no. 42406) that contains the cooling meter value in kWh. Similar to the heat meter registers for the heating and hot water, the format is an unsigned 4 byte value with a factor of 10.

I added the register to my item definition file and the debug output shows that it is read from the heat pump (the menu on the heat pump shows 3228 kWh):

Number:Energy           nibe_sensor_HeatMeterPassiveCool    "Passive Cooling [kWh]"                                          (gNibePump)          { channel="nibeheatpump:f1x55-udp:nibe1155:sensor#42406"}

2022-06-09 19:48:07.140 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Time to refresh variable '42406' data
2022-06-09 19:48:07.141 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Sending message: Message type = MODBUS_READ_REQUEST_MSG, Coil address = 42406
2022-06-09 19:48:09.133 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Received message: Message type = MODBUS_READ_RESPONSE_MSG, Coil address = 42406, Value = 32280
2022-06-09 19:48:09.134 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Received variable update: {Coil address = 42406, Value = 32280}
2022-06-09 19:48:09.135 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Unknown register 42406

Obviously, the item is not updated since the register is unknown to the binding. I thus added the register to the model description source code (F1X55.java):

put(42406, new VariableInformation(  10, NibeDataType.U32, Type.SENSOR  , "Heat Meter - Passive Cooling"));

After recompiling the binding, putting the .jar file into the addons directory and restarting OpenHab, the register can be read but a NullPointerException occurs.

2022-06-09 20:16:56.303 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Time to refresh variable '42406' data
2022-06-09 20:16:56.304 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Sending message: Message type = MODBUS_READ_REQUEST_MSG, Coil address = 42406
2022-06-09 20:16:56.306 [DEBUG] [ump.internal.connection.UDPConnector] - Sending request: C06902A6A5A8
2022-06-09 20:16:58.275 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Received message: Message type = MODBUS_READ_RESPONSE_MSG, Coil address = 42406, Value = 32280
2022-06-09 20:16:58.278 [DEBUG] [internal.handler.NibeHeatPumpHandler] - Received variable update: {Coil address = 42406, Value = 32280}
2022-06-09 20:16:58.280 [DEBUG] [internal.handler.NibeHeatPumpHandler] - 42406:Heat Meter - Passive Cooling/10 = 32280
2022-06-09 20:16:58.282 [WARN ] [mmon.WrappedScheduledExecutorService] - Scheduled runnable ended with an exception: 
java.lang.NullPointerException: null
	at org.openhab.binding.nibeheatpump.internal.handler.NibeHeatPumpHandler.handleVariableUpdate(NibeHeatPumpHandler.java:571) ~[?:?]
	at org.openhab.binding.nibeheatpump.internal.handler.NibeHeatPumpHandler$1.run(NibeHeatPumpHandler.java:123) ~[?:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) ~[?:?]
	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) ~[?:?]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
	at java.lang.Thread.run(Thread.java:829) [?:?]

I uninstalled the original binding (v3.2) and cleared the OH cache but the exception still occurs.

Did I miss something? Any help is appreciated!

Best regards,
Chris