Fixed error on Android when disabling editor in example app

packages/zefyr/lib/src/widgets/selection.dart

@@ -173,6 +173,9 @@ class _ZefyrSelectionOverlayState extends State<ZefyrSelectionOverlay>
   bool _didCaretTap = false;
 
   void _updateToolbar() {
+    if (!mounted) {
+      return;
+    }
     final editor = ZefyrEditor.of(context);
     final selection = editor.selection;
     final focusOwner = editor.focusOwner;

packages/zefyr/test/testing.dart

@@ -26,7 +26,7 @@ class EditorSandBox {
     document ??= NotusDocument.fromDelta(delta);
     var controller = ZefyrController(document);
 
-    Widget widget = ZefyrEditor(controller: controller, focusNode: focusNode);
+    Widget widget = _ZefyrSandbox(controller: controller, focusNode: focusNode);
     if (theme != null) {
       widget = ZefyrTheme(data: theme, child: widget);
     }
@@ -52,6 +52,12 @@ class EditorSandBox {
     return tester.pumpAndSettle();
   }
 
+  Future<void> disable() {
+    _ZefyrSandboxState state = tester.state(find.byType(_ZefyrSandbox));
+    state.disable();
+    return tester.pumpAndSettle();
+  }
+
   Future<void> tapEditor() async {
     await tester.pumpWidget(widget);
     await tester.tap(find.byType(ZefyrParagraph).first);
@@ -91,3 +97,32 @@ class EditorSandBox {
         matching: find.byType(Positioned));
   }
 }
+
+class _ZefyrSandbox extends StatefulWidget {
+  const _ZefyrSandbox({Key key, this.controller, this.focusNode})
+      : super(key: key);
+  final ZefyrController controller;
+  final FocusNode focusNode;
+
+  @override
+  _ZefyrSandboxState createState() => _ZefyrSandboxState();
+}
+
+class _ZefyrSandboxState extends State<_ZefyrSandbox> {
+  bool _enabled = true;
+
+  @override
+  Widget build(BuildContext context) {
+    return new ZefyrEditor(
+      controller: widget.controller,
+      focusNode: widget.focusNode,
+      enabled: _enabled,
+    );
+  }
+
+  void disable() {
+    setState(() {
+      _enabled = false;
+    });
+  }
+}

packages/zefyr/test/widgets/editor_test.dart

@@ -36,5 +36,14 @@ void main() {
       expect(editor.findSelectionHandle(), findsNothing);
       expect(editor.selection, TextSelection.collapsed(offset: 3));
     });
+
+    testWidgets('toggle enabled state', (tester) async {
+      final editor = new EditorSandBox(tester: tester);
+      await editor.tapEditor();
+      await editor.updateSelection(base: 0, extent: 3);
+      await editor.disable();
+      ZefyrEditor widget = tester.widget(find.byType(ZefyrEditor));
+      expect(widget.enabled, isFalse);
+    });
   });
 }