Performance improvement by disabling 2 presence callback per friend + fixed potential crash

app/src/main/java/org/linphone/settings/LinphonePreferences.java

@@ -1415,6 +1415,7 @@ public class LinphonePreferences {
     }
 
     public boolean isDarkModeEnabled() {
+        if (getConfig() == null) return false;
         return getConfig()
                 .getBool(
                         "app",

app/src/main/res/raw/linphonerc_factory

@@ -28,6 +28,7 @@ displaytype=MSAndroidTextureDisplay
 enable_basic_to_client_group_chat_room_migration=0
 enable_simple_group_chat_message_state=0
 aggregate_imdn=1
+notify_each_friend_individually_when_presence_received=0
 
 [app]
 activation_code_length=4