fix: add reactInstance condition in onHostDestroy

Author: r0h0gg6

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactDelegate.java

@@ -149,8 +149,10 @@ public void onHostDestroy() {
     if (ReactNativeFeatureFlags.enableBridgelessArchitecture()) {
       mReactHost.onHostDestroy(mActivity);
     } else {
-      if (getReactNativeHost().hasInstance()) {
-        getReactNativeHost().getReactInstanceManager().onHostDestroy(mActivity);
+      if (getReactNativeHost() != null) {
+        if (getReactNativeHost().hasInstance() && getReactNativeHost().getReactInstanceManager() != null) {
+            getReactNativeHost().getReactInstanceManager().onHostDestroy(mActivity);
+        }
       }
     }
   }
@@ -311,9 +313,9 @@ public void unloadApp() {
         mReactSurface = null;
       }
     } else {
-      if (mReactRootView != null) {
-        mReactRootView.unmountReactApplication();
-        mReactRootView = null;
+      if (this.mReactRootView != null) {
+        this.mReactRootView.unmountReactApplication();
+        this.mReactRootView = null;
       }
     }
   }