title: Flutter : Unhandled Exception: type 'String' is not a subtype of type 'int' of 'index'
body: <p>I'm working on flutter/firebase project. And there is some issue in this code :</p>
  <pre><code>db = FirebaseDatabase.instance.reference().child(&quot;Volunteers/&quot;+vname);
          db.once().then((DataSnapshot snapshot){
            Map&lt;dynamic, dynamic&gt; values = snapshot.value;
            values.forEach((key,values) {
                print(values[&quot;cont&quot;]);
            });
          });
  </code></pre>
  <p>Upon running, I get this error <code>Unhandled Exception: type 'String' is not a subtype of type 'int' of 'index'</code>
  Please help</p>