Fixed PR review comments

Author: rajdakin

interpreter/valid/valid.ml

@@ -127,7 +127,7 @@ let check_limits {min; max} range at msg =
 
 let check_def_type (c : context) (t : def_type) at =
   match t with
-  | DefT (RecT sts, i) -> assert Int32.(compare i (of_int (List.length sts)) < 0)
+  | DefT (RecT sts, i) -> assert (i < Lib.List32.length sts)
 
 let check_num_type (c : context) (t : num_type) at =
   ()

test/core/tag.wast

@@ -21,6 +21,14 @@
 ;;   "non-empty tag result type"
 ;; )
 
+;; Mutually recursive types
+(module
+  (rec
+    (type $f (func (param (ref null $c))))
+    (type $c (cont $f))
+  )
+  (tag (type $f))
+)
 
 ;; Link-time typing