patch 8.2.2387: runtime type check does not mention argument index

Problem:    Runtime type check does not mention argument index.
Solution:   Add ct_arg_idx. (closes #7720)
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 50dc2a0..06b5ecd 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -263,7 +263,7 @@
   CheckDefFailure(['extend({a: 1}, {b: 2}, 1)'], 'E1013: Argument 3: type mismatch, expected string but got number')
 
   CheckDefFailure(['extend([1], ["b"])'], 'E1013: Argument 2: type mismatch, expected list<number> but got list<string>')
-  CheckDefExecFailure(['extend([1], ["b", 1])'], 'E1012: Type mismatch; expected list<number> but got list<any>')
+  CheckDefExecFailure(['extend([1], ["b", 1])'], 'E1013: Argument 2: type mismatch, expected list<number> but got list<any>')
 enddef
 
 def Test_extendnew()