title: Why does the Null check operator used on a null value trigger here?
body: <p>Hey I have trouble with the Null check operator used on a null value error. In general I nearly have no problems with this, just in one case.</p>
  <p>So I have a site where you can chose between two options &amp; this works always, but in this one case not</p>
  <p><a href="https://i.stack.imgur.com/Jq65P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Jq65P.png" alt="here" /></a></p>
  <p>Because of that I thought that I have flaws in my Dataset, so that a value just isnt defined. I checked &amp; it seemed correct:</p>
  <p>Here I coppied in a part of the flawed data:</p>
  <pre><code>                       {
                        &quot;title&quot;:&quot;105 PS&quot;,
                        &quot;unterscheidungsData&quot;:[
                           {
                              &quot;difference&quot;:&quot;Hubraum 1422 cm³&quot;,
                              &quot;title&quot;:&quot;1.4 TDI DPF BlueMotion Technology&quot;,
                              &quot;wholeText &quot;:&quot;Ölverlust\n\nBremse\n\nBatterie(2009-2013)\n\nSteuerkette(2009 - 2011)\n\nZündspule(2009 - 2010)\n\nZündkerze(2009 - 2013)\n\nScheinwerfer(2010)&quot;
                           },
                           {
                              &quot;difference &quot;:&quot;Hubraum 1598 cm³&quot;,
                              &quot;title &quot;:&quot;1.6 TDI(DPF)&quot;,
                              &quot;wholeText &quot;:&quot;Ölverlust\n\nBremse\n\nBatterie(2009-2013)\n\nSteuerkette(2009 - 2011)\n\nZündspule(2009 - 2010)\n\nZündkerze(2009 - 2013)\n\nScheinwerfer(2010)&quot;
                           }
                        ]
                     }
  </code></pre>
  <p>&amp; here is data that works perfectly fine, I compared them &amp; didnt really notice any differences in the syntax</p>
  <pre><code>                      {
                        &quot;title&quot;:&quot;150 PS&quot;,
                        &quot;unterscheidungsData&quot;:[
                           {
                              &quot;difference&quot;:&quot;Sportwagen, Crosswagon&quot;,
                              &quot;title&quot;:&quot;1.9 16V JTD M-Jet&quot;,
                              &quot;wholeText&quot;:&quot;abbrechende Drallklappen können zu Turbo- oder Motorschaden führen\n\nDefekte Ölpumpen\n\nDefekte Lichtmaschinen\n\nverschlissene Zweimassenschwungräder\n\nVerrußte und hängende Abgasrückführungsventile\n\nAusfall Bremsservo\n\nUndichte Wasserkühler auf der Innenseite\n\ngerissene Keilrippenriemen\n\ndefekte Anlasser&quot;
                           },
                           {
                              &quot;difference&quot;:&quot;Normal&quot;,
                              &quot;title&quot;:&quot;2.4 10V JTD&quot;,
                              &quot;wholeText&quot;:&quot;Verrußte und hängende Abgasrückführungsventile\n\nAusfall Bremsservo\n\nUndichte Wasserkühler auf der Innenseite\n\ngerissene Keilrippenriemen\n\ndefekte Anlasser\n\nBeschädigungen der Ölwanne&quot;
                           }
                        ]
                     },
  
                             
  </code></pre>
  <p>So lastly I thought that my code has some flaws (this is my listview builder):</p>
  <pre><code>ListView.builder(
            itemCount: this.leistungData!.unterscheidungsData!.length,
            itemBuilder: (context, index) =&gt; GestureDetector(
              onTap: () {
                Navigator.push(context,
                    MaterialPageRoute(builder: (context) =&gt; AutoProbleme(
                      variantData: variantData,
                      unterscheidungsData: leistungData!.unterscheidungsData![index],
                      modell: modell,
                      modelData: modelData,
                    )));
              },
              child: Container(
                margin: EdgeInsets.all(10),
                height: MediaQuery.of(context).size.height * 0.05,
                width: MediaQuery.of(context).size.width * 0.9,
                child: Align(
                  alignment: Alignment.center,
                  child: Text(
                    this.leistungData!.unterscheidungsData![index].difference!,
                    textScaleFactor: 1.4,
                  ),
                ),
                decoration: BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.circular(16)),
              ),
            )),
  </code></pre>
  <p>&amp; I have to say that I didnt find anything that would justify this behaviour. For me the data looks fine &amp; it works nearly always, but nevertheless I get this error. Do you have any ideas what the problem could be?</p>