patch 8.2.4314: test fails where lines are skipped

Problem:    Test fails where lines are skipped.
Solution:   Only give an error when not skipping commands.
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 4fa71d9..37459a7 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -1228,6 +1228,11 @@
 
   assert_fails('vim9script', 'E1038:')
   v9.CheckDefFailure(['vim9script'], 'E1038:')
+
+  # no error when skipping
+  if has('nothing')
+    vim9script
+  endif
 enddef
 
 def Test_script_var_shadows_function()