"Type 'TZDate' is not assignable to type 'ResultDate'" when using tz with the in context property for some date-fns functions.

[kai-moseley]

I'm not super sure whether this is best added to this project's issues or the main date-fns one!

When using the in context property with some functions, such as endOfDay, the following TS error is shown:

endOfDay(date, { in: options.in ?? tz('UTC')})

Leads to:

Type 'TZDate' is not assignable to type 'ResultDate'.
  'TZDate' is assignable to the constraint of type 'ResultDate', but 'ResultDate' could be instantiated with a different subtype of constraint 'Date'.

The function itself does work as expected, as seen in this sandbox, and the output is consistent with using UTCDate or similar to define the date. So this looks like a typing issue, rather than a functional one?

The docs seem to indicate that this should be fine, so I don't believe I'm doing anything crazy here :D