Event drop issue fix

packages/core/lib/analytics.dart

@@ -382,8 +382,9 @@ class Analytics with ClientMethods {
   Future _process(RawEvent event) async {
     applyRawEventData(event);
     if (state.isReady) {
+      final processedEvent = await _timeline.process(event);
       _flushPolicyExecuter.notify(event);
-      return _timeline.process(event);
+      return processedEvent;
     } else {
       _pendingEvents.add(event);
       return event;

packages/core/lib/plugins/queue_flushing_plugin.dart

@@ -42,7 +42,6 @@ class QueueFlushingPlugin extends UtilityPlugin {
         if (!_isPendingUpload) {
           _isPendingUpload = true;
           await _onFlush(events);
-          _state!.flush();
         }
       } finally {
         _isPendingUpload = false;

packages/core/lib/state.dart

@@ -244,8 +244,14 @@ class QueueState<T extends JSONSerialisable> extends PersistedState<List<T>> {
     await modifyState((state) async => setState([...state, t]));
   }
 
-  void flush({int? number}) {
-    setState([]);
+  Future<void> flush({int? number}) async{
+    final events = await state;
+    if(number==null || number >= events.length){
+      setState([]);
+      return;
+    }
+    events.removeRange(0, number);
+    setEvents(events);
   }
 
   @override

packages/core/lib/timeline.dart

@@ -104,10 +104,10 @@ class Timeline {
       for (var plugin in plugins) {
         if (result != null) {
           try {
-            final pluginResult = plugin.execute(result);
+            final pluginResult = await plugin.execute(result);
             // Each destination is independent from each other, so we don't roll over changes caused internally in each one of their processing
             if (type != PluginType.destination) {
-              result = await pluginResult;
+              result = pluginResult;
             }
           } catch (error) {
             reportInternalError(