Properly dispose of a TextEditingController

Author: PaulAllanSturm

lib/src/samples/query_feature_table_sample.dart

@@ -43,6 +43,12 @@ class QueryFeatureTableSampleState extends State<QueryFeatureTableSample> {
     scale: 100000000,
   );
 
+  @override
+  void dispose() {
+    _textEditingController.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(