chore: Make messageEvent.data cast safer and fix Android build

Author: abarker-launchdarkly

packages/event_source_client/lib/src/sse_client_html.dart

@@ -72,9 +72,11 @@ class HtmlSseClient implements SSEClient {
   void _handleMessageEvent(web.Event event) {
     _activeSince = DateTime.now().millisecondsSinceEpoch;
     final messageEvent = event as web.MessageEvent;
-    final ldMessageEvent = ld_message_event.MessageEvent(
-        messageEvent.type, (messageEvent.data as JSString).toDart, messageEvent.lastEventId);
-    _messageEventsController.sink.add(ldMessageEvent);
+    if (messageEvent.data != null && messageEvent.data.typeofEquals('string')) {
+      final ldMessageEvent = ld_message_event.MessageEvent(messageEvent.type,
+          (messageEvent.data as JSString).toDart, messageEvent.lastEventId);
+      _messageEventsController.sink.add(ldMessageEvent);
+    }
   }
 
   /// Subscribe to this [stream] to receive events and sometimes errors.  The first

packages/flutter_client_sdk/example/android/app/src/main/AndroidManifest.xml

@@ -1,4 +1,5 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <uses-permission android:name="android.permission.INTERNET" />
     <application
         android:label="example"
         android:name="${applicationName}"

packages/flutter_client_sdk/example/android/gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip

packages/flutter_client_sdk/example/android/settings.gradle

@@ -18,8 +18,8 @@ pluginManagement {
 
 plugins {
     id "dev.flutter.flutter-plugin-loader" version "1.0.0"
-    id "com.android.application" version "7.3.0" apply false
-    id "org.jetbrains.kotlin.android" version "1.7.10" apply false
+    id "com.android.application" version "8.3.0" apply false
+    id "org.jetbrains.kotlin.android" version "1.8.10" apply false
 }
 
 include ":app"