define-type's error message adds extra parens

[robby@…]

This program:

#lang planet plai/plai:1:16
(define-type t (c))
(type-case t (list 1) (c () 1))

produces the error message:

type-case: this value ((1)) is not of the specified type

but the extra pair of parens is confusing. I think better to stick with the standard error message style, ie something like:

type-case: expected a value from type t, got: (1)

[plai]

will be fixed in next release