Fix internal error for vector type-checking

If multiple values were expected and not provided
when type-checking a vector expression, TR would throw
an internal error.

Thanks to Pierpaolo for the report!

(cherry picked from commit 29bce22d0b)

collects/tests/typed-racket/fail/internal-vector-error.rkt

@@ -0,0 +1,13 @@
+#;
+(exn:pred #rx"expected 2 values, but got 1")
+#lang typed/racket
+
+;; This test ensures that the following snippet doesn't
+;; result in an internal error.
+;;
+;; see
+;; http://lists.racket-lang.org/dev/archive/2013-January/011614.html
+
+(: f (-> (Values String (Vector Integer Integer))))
+(define (f) (vector 1 2))
+

collects/typed-racket/typecheck/tc-app/tc-app-hetero.rkt

@@ -136,4 +136,4 @@
        (ret (make-HeterogeneousVector
               (for/list ((e (in-syntax #'(args ...))))
                 (generalize (tc-expr/t e)))))]
-      [_ (int-err "bad expected: ~a" expected)])))
+      [_ (ret Err)])))