NULLPointerException , when characterstics is null

[RotBolt]

Describe the bug
In GattClient, while connecting to gatt , if characterstic is null, it generates Unhandled Exception

To Reproduce
just try to connect any BLE device

Expected behavior
Handle this exception

Logs

Screenshots

2019-03-09 12:36:48.080 22582-22603/com.nilhcem.blenamebadge W/BluetoothGatt: Unhandled exception in callback
    java.lang.NullPointerException: Attempt to invoke virtual method 'int android.bluetooth.BluetoothGattCharacteristic.getProperties()' on a null object reference
        at android.bluetooth.BluetoothGatt.writeCharacteristic(BluetoothGatt.java:1155)
        at com.nilhcem.blenamebadge.device.bluetooth.GattClient.writeNextData(GattClient.kt:72)
        at com.nilhcem.blenamebadge.device.bluetooth.GattClient.writeDataStart(GattClient.kt:60)
        at com.nilhcem.blenamebadge.ui.message.MessagePresenter$sendBytes$2$3.invoke(MessagePresenter.kt:49)
        at com.nilhcem.blenamebadge.ui.message.MessagePresenter$sendBytes$2$3.invoke(MessagePresenter.kt:14)
        at com.nilhcem.blenamebadge.device.bluetooth.GattClient$gattCallback$1.onServicesDiscovered(GattClient.kt:42)
        at android.bluetooth.BluetoothGatt$1$5.run(BluetoothGatt.java:328)
        at android.bluetooth.BluetoothGatt.runOrQueueCallback(BluetoothGatt.java:770)
        at android.bluetooth.BluetoothGatt.access$200(BluetoothGatt.java:39)
        at android.bluetooth.BluetoothGatt$1.onSearchComplete(BluetoothGatt.java:323)
        at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:111)
        at android.os.Binder.execTransact(Binder.java:731)
2019-03-09 12:36:48.138 22582-22603/com.nilhcem.blenamebadge D/BluetoothGatt: onConnectionUpdated() - Device=D3:C3:10:49:09:D8 interval=36 latency=0 timeout=500 status=0

Smartphone Info:
Device : Nokia 6.1
Android Version : 9.0 android pie

Would you like to work on the issue?
Yes