Exception during flutter overlay insert stating entry is already present in target Overlay

I am trying to show an overlay widget whenever the software keyboard appears on the screen. The overlay appears at the top of the keyboard. I've included the code below. I'm stuck in a problem with exception stating "Flutter Error. The specified entry is already present in the target Overlay". I am not sure how to fix this. Can someone help?

Code:

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: const MyHomePage(),
    );
  }
}

class KeyboardAwareWidget extends StatefulWidget {
  final Widget child;
  final Widget? keyboardWidget;

  const KeyboardAwareWidget({
    required this.child,
    this.keyboardWidget,
    Key? key,
  }) : super(key: key);

  @override
  State<KeyboardAwareWidget> createState() => _KeyboardAwareWidgetState();
}

class _KeyboardAwareWidgetState extends State<KeyboardAwareWidget> {
  OverlayEntry? _overlayEntry;

  @override
  void initState() {
    super.initState();
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _rebuildOverlay();
  }

  void _rebuildOverlay() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      final mediaQuery = MediaQuery.of(context);
      final keyboardHeight = mediaQuery.viewInsets.bottom;

      if (keyboardHeight > 0) {
        // Show the overlay only when the keyboard is visible.
        _showOverlay(keyboardHeight);
      } else {
        _hideOverlay();
      }
    });
  }

  void _showOverlay(double keyboardHeight) {
    _overlayEntry ??= OverlayEntry(
      builder:
          (context) => Positioned(
            bottom: keyboardHeight,
            left: 0,
            right: 0,
            child: Material(
              elevation: 8.0,
              child: widget.keyboardWidget ?? Container(),
            ),
          ),
    );

    Overlay.of(context).insert(_overlayEntry!);
  }

  void _hideOverlay() {
    _overlayEntry?.remove();
    _overlayEntry = null;
  }

  @override
  void dispose() {
    _hideOverlay();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return widget.child;
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Keyboard Aware Widget')),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const TextField(
                decoration: InputDecoration(hintText: 'Tap to show keyboard'),
              ),
              const SizedBox(height: 20),
              ElevatedButton(onPressed: () {}, child: const Text('A Button')),
            ],
          ),
        ),
      ),
      bottomNavigationBar: KeyboardAwareWidget(
        child: Container(
          height: 100,
          color: Colors.amber,
          child: const Center(child: Text('Main Content')),
        ),
        keyboardWidget: Container(
          height: 50,
          color: Colors.blue,
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: [
              IconButton(onPressed: () {}, icon: const Icon(Icons.add)),
              IconButton(onPressed: () {}, icon: const Icon(Icons.remove)),
              IconButton(onPressed: () {}, icon: const Icon(Icons.send)),
            ],
          ),
        ),
      ),
    );
  }
}