patch 8.2.3249: Vim9: error for re-imported function with default argument

Problem:    Vim9: error for re-imported function with default argument.
Solution:   Do not check argument type if it is still unknown. (closes #8653)
diff --git a/src/eval.c b/src/eval.c
index 0d41f17..769816d 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3359,7 +3359,7 @@
 	{
 	    type_T *actual = typval2type(rettv, get_copyID(), &type_list, TRUE);
 
-	    if (!equal_type(want_type, actual))
+	    if (!equal_type(want_type, actual, 0))
 	    {
 		if (want_type == &t_bool && actual != &t_bool
 					&& (actual->tt_flags & TTFLAG_BOOL_OK))