Unknown error in custom widget... widget still works?

I am learning to build a custom widget adding one thing at a time. 
Im at adding a container with height, weight, color, 
and a single basic line of text inside the containerHowever, 
I am getting an unknown error and yet the widget works. Any ideas?

// Automatic FlutterFlow imports
import '/backend/schema/structs/index.dart';
import '/backend/supabase/supabase.dart';
import '/actions/actions.dart' as action_blocks;
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 '/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!

class CodeVisualizerV1Widget extends StatefulWidget {
  const CodeVisualizerV1Widget({
    super.key,
    this.width,
    this.height,
    this.customColor,
    this.data,
  });

  final double? width;
  final double? height;
  final Color? customColor;
  final String? data;

  @override
  State<CodeVisualizerV1Widget> createState() => _CodeVisualizerV1WidgetState();
}

class _CodeVisualizerV1WidgetState extends State<CodeVisualizerV1Widget> {
  @override
  Widget build(BuildContext context) {
    return Container(
      width: widget.width ?? 100.0,
      height: widget.height ?? 100.0,
      color: widget.customColor ?? Colors.blue,
      child: Center(
        child: Text(widget.data ?? 'No Data'),
      ),
    );
  }
}