When passing the empty string to Date Type, it occurs string index out of range error

[KaniKim]

When I passed a empty string to Date Field, It occurs GraphQL 400 error, with message, "IndexError: string index out of range"
And then I found that aniso8601 module occurs this error. Are there any solutions to prevent this one?

Well, I can just pass a null to Date, but I think there is more improvement to this packages.