From 116f16b470e58c6633ced07333edb9a072bc82a0 Mon Sep 17 00:00:00 2001
From: yanyongyu <yanyongyu_1@126.com>
Date: Sat, 28 Aug 2021 19:39:54 +0800
Subject: [PATCH] :bug: fix stringify when formatting

---
 nonebot/adapters/_formatter.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/nonebot/adapters/_formatter.py b/nonebot/adapters/_formatter.py
index 68994f42..0e1e59b7 100644
--- a/nonebot/adapters/_formatter.py
+++ b/nonebot/adapters/_formatter.py
@@ -103,3 +103,6 @@ class MessageFormatter(Formatter, Generic[TM]):
 
         return self.factory(functools.reduce(operator.add, results or
                                              [""])), auto_arg_index
+
+    def format_field(self, value: Any, format_spec: str) -> Any:
+        return super().format_field(value, format_spec) if format_spec else None