patch 9.0.0221: accessing freed memory if compiling nested function fails

Problem:    Accessing freed memory if compiling nested function fails.
Solution:   Mess up the variable name so that it won't be found.
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 5c75457..fd7182d 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -911,6 +911,18 @@
   v9.CheckScriptFailure(lines, 'E1173: Text found after enddef: burp', 3)
 enddef
 
+def Test_nested_function_fails()
+  var lines =<< trim END
+      def T()
+        def Func(g: string):string
+        enddef
+        Func()
+      enddef
+      silent! defcompile
+  END
+  v9.CheckScriptFailure(lines, 'E1069:')
+enddef
+
 def Test_not_nested_function()
   echo printf('%d',
       function('len')('xxx'))