Fix argparser (#5421)

fixed the issue caused by regression 


## For community
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comment**

tests/test_cli_utils.py

@@ -77,3 +77,15 @@ def test_parser_hooking():
         "zsh",
         "bash",
     )
+
+
+def test_parser_default_func(mocker):
+    import xonsh.xontribs as xx
+
+    alias = xx.XontribAlias()
+
+    def func():
+        return True
+
+    mocker.patch.object(xx, "xontribs_list", func)
+    assert alias([]) is True

xonsh/cli_utils.py

@@ -208,10 +208,6 @@ def add_args(
             action.help += " (type: %(type)s)"
 
 
-def empty_help_func(_parser, _stdout):
-    _parser.print_help(file=_stdout)
-
-
 def make_parser(
     func: tp.Union[tp.Callable, str],
     empty_help=False,
@@ -226,7 +222,7 @@ def make_parser(
             kwargs["epilog"] = doc.epilog
     parser = ArgParser(**kwargs)
     if empty_help:
-        parser.set_defaults(**{_FUNC_NAME: empty_help_func})
+        parser.default_command = "--help"
     return parser
 
 
@@ -410,8 +406,9 @@ def dispatch(parser: ap.ArgumentParser, args=None, lenient=False, **ns):
     ns["_parsed"] = parsed
     ns.update(vars(parsed))
 
-    func = ns[_FUNC_NAME]
+    if _FUNC_NAME in ns:
-    return _dispatch_func(func, ns)
+        func = ns[_FUNC_NAME]
+        return _dispatch_func(func, ns)
 
 
 class ArgparseCompleter:

xonsh/xontribs.py

@@ -399,7 +399,7 @@ class XontribAlias(ArgParserAlias):
         parser.add_command(xontribs_load, prog="load")
         parser.add_command(xontribs_unload, prog="unload")
         parser.add_command(xontribs_reload, prog="reload")
-        parser.add_command(xontribs_list, prog="list")
+        parser.add_command(xontribs_list, prog="list", default=True)
         return parser