title: Null check operator used on a null value, Relevant Error causing widget was Material App
body: <p>The app was working just fine till I used listview.builder and added a list of items (mentioned in datalist)  I am unable to understand what exactly is causing the error since there's no error showing in the IDE itself. Can anyone explain what is happening here and possibly give me a solution?</p>
  <p>Thanks in advance!</p>
  <p>Finance Page:</p>
  <pre><code> import 'package:flutter/material.dart';
  
  class FinancePage extends StatefulWidget {
    const FinancePage({Key? key}) : super(key: key);
  
    @override
    _FinancePageState createState() =&gt; _FinancePageState();
  }
  
  class _FinancePageState extends State&lt;FinancePage&gt; {
  
    final List&lt;DataTiles&gt; dataList = [
      DataTiles(title: &quot;Mobile Home Dealers&quot;, subtitle: &quot;Last payment 17 May&quot;,color: Colors.deepPurpleAccent.shade50),
      DataTiles(title: &quot;Taxicabs and Limousines&quot;, subtitle: &quot;Last payment 26 May&quot;,color: Colors.lightBlueAccent),
      DataTiles(title: &quot;Miscellaneous Apparel and Accessory Shops&quot;, subtitle: &quot;Last payment 06 April&quot;,color: Colors.redAccent),
      DataTiles(title: &quot;Electric, Gas, Sanitary and Water utilities&quot;, subtitle: &quot;Last payment 01 May&quot;,color: Colors.deepPurpleAccent.shade50),
      DataTiles(title: &quot;Misc. General Merchandise&quot;, subtitle: &quot;Last payment 01 March&quot;,color: Colors.lightBlueAccent),
    ];
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        backgroundColor: Colors.deepPurple.shade800,
        body: Column(
          children: [
            const SizedBox(
              height: 100,
            ),
            Padding(
                padding: const EdgeInsets.all(10),
                child: Card(
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(5),
                  ),
                  elevation: 3,
                  child: ListTile(
                      shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(5),
                      ),
                      tileColor: Colors.deepPurpleAccent,
                      leading: const Text(
                        &quot;Card balance&quot;,
                        style: TextStyle(color: Colors.white),
                      ),
                      trailing: FittedBox(
                        fit: BoxFit.fill,
                        child: Row(
                          children: const [
                            Text(
                              &quot;0₹&quot;,
                              style: TextStyle(color: Colors.white),
                            ),
                            Icon(
                              Icons.arrow_forward_ios,
                              color: Colors.white,
                              size: 10,
                            )
                          ],
                        ),
                      )),
                )),
            const Text(&quot;PAYMENT CATEGORIES&quot;,
                style: TextStyle(
                  color: Colors.grey,
                )),
               SizedBox(
                 height: 200,
                 child: ListView.builder(
                     scrollDirection: Axis.horizontal,
                     itemCount: dataList.length,
                     itemBuilder: (context, index) {
                       return  SizedBox(
                         width: 170,
                         child: Card(
                           child: Column(
                             children: [
                               Text(dataList[index].title,
                                   style: const TextStyle(
                                     fontSize: 20,
                                   ),
                               ),
                               Text(dataList[index].subtitle,),
                             ],
                           ),
                           shape: RoundedRectangleBorder(
                             borderRadius: BorderRadius.circular(10),
                           ),
                           color: dataList[index].color,
                         ),
                       );
                     }),
               ),
          ],
        ),
      );
    }
  }
  
  class DataTiles {
    DataTiles({required this.title, required this.subtitle, required this.color});
    final String title;
    final String subtitle;
    final Color color;
  }
  </code></pre>
  <p>main.dart</p>
  <pre><code>import 'package:flutter/material.dart';
  
  import 'finance_page.dart';
  
  void main() {
    WidgetsFlutterBinding.ensureInitialized();
    runApp(const MyApp());
  }
  
  class MyApp extends StatelessWidget {
    const MyApp({Key? key}) : super(key: key);
  
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return  const MaterialApp(
        title: 'Flutter Demo',
        home: FinancePage(),
      );
    }
  }
  </code></pre>