dp3t-app-ios can receive ephIDs but dp3t-app-android fails to receive ephIDs from iOS

[0xjams]

After building the iOS app, and leaving the two devices exchanging ephIDs, if the android device reports a disease, the iOS device will get a notification, but the reverse does not work.

The issue was traced to the fact that when iOS starts to send ephIDs to Android, the following exception occurs:

/org.dpppt.android.app E/BluetoothGattCallback: Failed to initiate characteristic read
2020-04-28 03:40:50.541 31207-31219/org.dpppt.android.app W/BluetoothGatt: Unhandled exception in callback
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.bluetooth.BluetoothGattCallback.onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)' on a null object reference
at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:229)
at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:70)
at android.os.Binder.execTransact(Binder.java:573)