mutate_exists for StorageValue with ValueQuery

[xlc]

I use ValueQuery so it creates a default value for empty key, which is handy. But I still want to delete it with mutate_exists.

[bkchr]

mutate_exists doesn't exist for StorageValue? Do you mean StorageMap? And what is the issue? The value is not deleted when you set the mutated value to None?

[xlc]

Sorry for not be clear. I am requesting add mutate_exists for StorageValue