patch 9.1.1279: Vim9: null_object and null_class are no reserved names

Problem:  Vim9: null_object and null_class are no reserved names
Solution: Add null_object and null_class as reserved names.
          (Yegappan Lakshmanan)

closes: #17054

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 97c11a7..2294936 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -326,6 +326,8 @@
                'null_list',
                'null_partial',
                'null_string',
+               'null_object',
+               'null_class',
                ] + more_names
     v9.CheckDefExecAndScriptFailure(['var ' .. name .. ' =  0'], 'E1034:')
     v9.CheckDefExecAndScriptFailure(['var ' .. name .. ': bool'], 'E1034:')