patch 9.0.0230: no error for comma missing in list in :def function

Problem:    No error for comma missing in list in :def function.
Solution:   Check for missing comma. (closes #10943)
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 597e31e..d0785dc 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -3274,7 +3274,7 @@
 
   v9.CheckScriptSuccess([
       'vim9script',
-      'new'
+      'new',
       'setline(1, ["# define pat", "last"])',
       ':$',
       'dsearch /pat/ #comment',
@@ -3283,7 +3283,7 @@
 
   v9.CheckScriptFailure([
       'vim9script',
-      'new'
+      'new',
       'setline(1, ["# define pat", "last"])',
       ':$',
       'dsearch /pat/#comment',