patch 8.2.3100: Vim9: no error when using type with unknown number of args

Problem:    Vim9: no error when using type with unknown number of arguments.
Solution:   Do not ignore argument count of -1. (closes #8492)
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 22c68f4..1e99e95 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -57,7 +57,7 @@
       assert_equal(function('len'), Res)
 
       var RetOne: func(string): number = function('len')
-      var RetTwo: func(string): number = function('winnr')
+      var RetTwo: func(string): number = function('charcol')
       var RetThat: func = g:atrue ? RetOne : RetTwo
       assert_equal(function('len'), RetThat)