fix: prevent crash when cleaning up uninitialized SDK on destroy

* Wrap removeHandlers() and removeObservers() calls in try-catch blocks within onHostDestroy() and onCatalystInstanceDestroy() to handle cases where the native OneSignal SDK throws "Must call 'initWithContext' before use" during activity destruction.
* Also move the oneSignalInitDone flag further down past the native `OneSignal.initWithContext(context, appId)` call.

Author: nan-li

android/src/main/java/com/onesignal/rnonesignalandroid/RNOneSignal.java

@@ -172,6 +172,11 @@ public void onClick(INotificationClickEvent event) {
     };
 
     private void removeObservers() {
+        if(!oneSignalInitDone) {
+            Logging.debug("OneSignal React-Native SDK not initialized yet. Could not remove observers.", null);
+            return;
+        }
+
         this.removePermissionObserver();
         this.removePushSubscriptionObserver();
         this.removeUserStateObserver();
@@ -226,8 +231,12 @@ public String getName() {
 
     @Override
     public void onHostDestroy() {
-        removeHandlers();
-        removeObservers();
+        try {
+            removeHandlers();
+            removeObservers();
+        } catch (Exception e) {
+            Logging.debug("OneSignal SDK not fully initialized. Could not remove handlers/observers: " + e.getMessage(), null);
+        }
     }
 
     @Override
@@ -238,8 +247,12 @@ public void onHostResume() {}
 
     @Override
     public void onCatalystInstanceDestroy() {
-        removeHandlers();
-        removeObservers();
+        try {
+            removeHandlers();
+            removeObservers();
+        } catch (Exception e) {
+            Logging.debug("OneSignal SDK not fully initialized. Could not remove handlers/observers: " + e.getMessage(), null);
+        }
     }
 
     // OneSignal namespace methods
@@ -254,15 +267,14 @@ public void initialize(String appId) {
             return;
         }
 
-        oneSignalInitDone = true;
-
         if (context == null) {
             // in some cases, especially when react-native-navigation is installed,
             // the activity can be null, so we can initialize with the context instead
             context = mReactApplicationContext.getApplicationContext();
         }
 
         OneSignal.initWithContext(context, appId);
+        oneSignalInitDone = true;
     }
 
     @ReactMethod