The type of the right operand ('ConfirmAction') isn't a subtype or a > supertype of the left operand ('Future<ConfirmAction?>')

How to fix

The type of the right operand (‘ConfirmAction’) isn’t a subtype or a
supertype of the left operand (‘Future<ConfirmAction?>’).

this does not cause runtime errors, but it does show the recommendation in the IDE

return Dismissible(
      key: UniqueKey(),
      direction: DismissDirection.horizontal,
      onDismissed: (direction) async {
        await _asyncConfirmDialog(context).then((value) {    
          if (value == ConfirmAction.cancel) { //here
            ...

>Solution :

I don’t know what happens inside _asyncConfirmDialog, but it looks like the returned value is of type Future<Future<ConfirmAction?>>, which makes value has the type of Future<ConfirmAction?>. You need to put the await keyword to make it a ConfirmAction? (which is comparable to ConfirmAction)

await _asyncConfirmDialog(context).then((value) async { // (1) put async here    
  if (await value == ConfirmAction.cancel) { // (2) put await here