error when using expandable image in Custom Widget

// Automatic FlutterFlow imports
import '/backend/schema/structs/index.dart';
import '/backend/schema/enums/enums.dart';
import '/backend/supabase/supabase.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/widgets/index.dart'; // Imports other custom widgets
import '/custom_code/actions/index.dart'; // Imports custom actions
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom widget code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

import 'dart:convert';
import '/flutter_flow/flutter_flow_expanded_image_view.dart';

class Base64Image extends StatefulWidget {
  const Base64Image({
    Key? key,
    this.width,
    this.height,
    required this.base64,
  }) : super(key: key);
  final double? width;
  final double? height;
  final String? base64;
  @override
  _Base64ImageState createState() => _Base64ImageState();
}

class _Base64ImageState extends State<Base64Image> {
  @override
  Widget build(BuildContext context) {
    Uint8List? imageBytes;

    imageBytes = widget.base64 != null ? base64Decode(widget.base64!) : null;

    return imageBytes != null
        ? InkWell(
            onTap: () {
              // Your tap action here
              Navigator.push(
                context,
                PageTransition(
                  type: PageTransitionType.fade,
                  child: FlutterFlowExpandedImageView(
                    image: Image.memory(
                      imageBytes!,
                      fit: BoxFit.contain,
                      errorBuilder: (context, error, stackTrace) => Image.asset(
                        'assets/images/error_image.png',
                        fit: BoxFit.contain,
                      ),
                    ),
                    allowRotation: false,
                    tag: 'imageTag',
                    useHeroAnimation: true,
                  ),
                ),
              );
            },
            child: Image.memory(
              imageBytes,
              width: widget.width,
              height: widget.height,
              fit: BoxFit.cover,
            ),
          )
        : Container();
  }
}
// Set your widget name, define your parameter, and then add the
// boilerplate code using the green button on the right!