App error when trying to connect to Etekcity ESF24

[Oaklight]

Describe the bug
App error pops up as soon as connecting to the Bluetooth scale.

Reproduced with latest dev version: 2.5.3

Expected behavior
Not crash the app.

Debug log

Build version: 2.5.3 
Build date: 1981-01-01 01:01:02 
Current date: 2025-01-03 05:32:30 
Device: HUAWEI JAD-AL50 
OS version: Android 12 (SDK 31) 
 
Stack trace:  
java.lang.NullPointerException: no valid characteristic provided
	at j$.util.Objects.requireNonNull(Unknown Source:5)
	at com.welie.blessed.BluetoothPeripheral.writeCharacteristic(BluetoothPeripheral.java:1224)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.writeBytes(BluetoothCommunication.java:303)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.writeBytes(BluetoothCommunication.java:291)
	at com.health.openscale.core.bluetooth.BluetoothQNScale.onNextStep(BluetoothQNScale.java:111)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:610)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:612)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:612)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.resumeMachineState(BluetoothCommunication.java:210)
	at com.health.openscale.core.bluetooth.BluetoothCommunication$1.onServicesDiscovered(BluetoothCommunication.java:464)
	at com.welie.blessed.BluetoothPeripheral$1$1.run(BluetoothPeripheral.java:213)
	at android.os.Handler.handleCallback(Handler.java:966)
	at android.os.Handler.dispatchMessage(Handler.java:110)
	at android.os.Looper.loopOnce(Looper.java:205)
	at android.os.Looper.loop(Looper.java:293)
	at android.app.ActivityThread.loopProcess(ActivityThread.java:9986)
	at android.app.ActivityThread.main(ActivityThread.java:9975)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:586)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1240)

[Dwarf1er]

I also have an Etekcity ESF24 and got a crash when trying to connect

Describe the bug
App crashed when trying to connect to the scale

Expected behaviour
Connect to the scale without crashing the app

Debug log

Build version: 2.5.3 
Build date: 1981-01-01 01:01:02 
Current date: 2025-01-03 15:43:32 
Device: Google Pixel 7a 
OS version: Android 15 (SDK 35) 
 
Stack trace:  
java.lang.NullPointerException: no valid characteristic provided
	at j$.util.Objects.requireNonNull(Unknown Source:5)
	at com.welie.blessed.BluetoothPeripheral.writeCharacteristic(BluetoothPeripheral.java:1224)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.writeBytes(BluetoothCommunication.java:303)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.writeBytes(BluetoothCommunication.java:291)
	at com.health.openscale.core.bluetooth.BluetoothQNScale.onNextStep(BluetoothQNScale.java:111)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:610)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:612)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.nextMachineStep(BluetoothCommunication.java:612)
	at com.health.openscale.core.bluetooth.BluetoothCommunication.resumeMachineState(BluetoothCommunication.java:210)
	at com.health.openscale.core.bluetooth.BluetoothCommunication$1.onServicesDiscovered(BluetoothCommunication.java:464)
	at com.welie.blessed.BluetoothPeripheral$1$1.run(BluetoothPeripheral.java:213)
	at android.os.Handler.handleCallback(Handler.java:991)
	at android.os.Handler.dispatchMessage(Handler.java:102)
	at android.os.Looper.loopOnce(Looper.java:232)
	at android.os.Looper.loop(Looper.java:317)
	at android.app.ActivityThread.main(ActivityThread.java:8826)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:591)
	at com.android.internal.os.ExecInit.main(ExecInit.java:50)
	at com.android.internal.os.RuntimeInit.nativeFinishInit(Native Method)
	at com.android.internal.os.RuntimeInit.main(RuntimeInit.java:369)