Handle tapping when no text yet on this line for checkbox list

lib/widgets/editor.dart

@@ -333,6 +333,10 @@ class _QuillEditorSelectionGestureDetectorBuilder
     containerNode.ChildQuery segmentResult =
         line.queryChild(result.offset, false);
     if (segmentResult.node == null) {
+      if (line.length == 1) {
+        // tapping when no text yet on this line
+        _flipListCheckbox(line, segmentResult);
+      }
       return;
     }
     Leaf segment = segmentResult.node as Leaf;
@@ -362,25 +366,31 @@ class _QuillEditorSelectionGestureDetectorBuilder
       }
       return;
     }
-    if (!getEditor().widget.readOnly &&
+    if (_flipListCheckbox(line, segmentResult)) {
-        segment.parent.style.containsKey(Attribute.list.key) &&
-        segmentResult.offset == 0) {
-      // segmentResult.offset == 0 means tap at the beginning of the TextLine
-      String listVal =
-          segment.parent.style.attributes[Attribute.list.key].value;
-      if (listVal == Attribute.unchecked.value) {
-        segment.parent.style.attributes
-            .update(Attribute.list.key, (value) => Attribute.checked);
-        getEditor().widget.controller.notifyChangeListeners();
-      } else if (listVal == Attribute.checked.value) {
-        segment.parent.style.attributes
-            .update(Attribute.list.key, (value) => Attribute.unchecked);
-        getEditor().widget.controller.notifyChangeListeners();
-      }
       return;
     }
   }
 
+  bool _flipListCheckbox(Line line, containerNode.ChildQuery segmentResult) {
+    if (getEditor().widget.readOnly ||
+        !line.style.containsKey(Attribute.list.key) ||
+        segmentResult.offset != 0) {
+      return false;
+    }
+    // segmentResult.offset == 0 means tap at the beginning of the TextLine
+    String listVal = line.style.attributes[Attribute.list.key].value;
+    if (listVal == Attribute.unchecked.value) {
+      line.style.attributes
+          .update(Attribute.list.key, (value) => Attribute.checked);
+      getEditor().widget.controller.notifyChangeListeners();
+    } else if (listVal == Attribute.checked.value) {
+      line.style.attributes
+          .update(Attribute.list.key, (value) => Attribute.unchecked);
+      getEditor().widget.controller.notifyChangeListeners();
+    }
+    return true;
+  }
+
   void _launchUrl(String url) async {
     if (!url.startsWith('http')) {
       url = 'https://$url';