Wrong type for custom scalar (e.g. Date)

[P4sca1]

I am using the following DateTime custom scalar.

export const DateTime = Graffle.Scalars.create('DateTime', {
	decode: (value: string) => new Date(value),
	encode: (value: Date) => formatRFC3339(value),
})

When I try to access date methods on a returned object, I get the following issue, because all method types are replaced with {}.