[ask][ermine] fix ask field crash

SY-1040 #done

Change-Id: I6954a6b77293638aa561abe9fbd6975a025a48d0
diff --git a/shell/ermine/lib/src/modules/ask_sheet.dart b/shell/ermine/lib/src/modules/ask_sheet.dart
index f4c5e3e..893e0e0 100644
--- a/shell/ermine/lib/src/modules/ask_sheet.dart
+++ b/shell/ermine/lib/src/modules/ask_sheet.dart
@@ -144,8 +144,12 @@
   }
 
   @override
-  Widget build(BuildContext context) => Offstage(
-        offstage: _visibilityState == _VisibilityStatus.hidden,
+  Widget build(BuildContext context) => Visibility(
+        maintainState: true,
+        maintainSize: true,
+        maintainAnimation: true,
+        maintainInteractivity: true,
+        visible: _visibilityState != _VisibilityStatus.hidden,
         child: IgnorePointer(
           ignoring: !_visible,
           child: LayoutBuilder(