🐛 fix union validation error (#1001)

nonebot/internal/adapter/event.py

@@ -1,4 +1,5 @@
 import abc
+from typing import Any, Type, TypeVar
 
 from pydantic import BaseModel
 
@@ -6,6 +7,8 @@ from nonebot.utils import DataclassEncoder
 
 from .message import Message
 
+E = TypeVar("E", bound="Event")
+
 
 class Event(abc.ABC, BaseModel):
     """Event 基类。提供获取关键信息的方法，其余信息可直接获取。"""
@@ -14,6 +17,12 @@ class Event(abc.ABC, BaseModel):
         extra = "allow"
         json_encoders = {Message: DataclassEncoder}
 
+    @classmethod
+    def validate(cls: Type["E"], value: Any) -> "E":
+        if isinstance(value, Event) and not isinstance(value, cls):
+            raise TypeError(f"{value} is incompatible with Event type {cls}")
+        return super().validate(value)
+
     @abc.abstractmethod
     def get_type(self) -> str:
         """获取事件类型的方法，类型通常为 NoneBot 内置的四种类型。"""