patch 8.2.1223: Vim9: invalid type error for function default value

Problem:    Vim9: invalid type error for function default value.
Solution:   Use right argument index. (closes #6458)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index f9c5a2a..3e90a02 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -104,11 +104,19 @@
   return name
 enddef
 
+def MyDefaultSecond(name: string, second: bool  = true): string
+  return second ? name : 'none'
+enddef
+
 def Test_call_default_args()
   assert_equal('string', MyDefaultArgs())
   assert_equal('one', MyDefaultArgs('one'))
   assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
 
+  assert_equal('test', MyDefaultSecond('test'))
+  assert_equal('test', MyDefaultSecond('test', true))
+  assert_equal('none', MyDefaultSecond('test', false))
+
   CheckScriptFailure(['def Func(arg: number = asdf)', 'enddef', 'defcompile'], 'E1001:')
   CheckScriptFailure(['def Func(arg: number = "text")', 'enddef', 'defcompile'], 'E1013: argument 1: type mismatch, expected number but got string')
 enddef