feat(异常处理): 改进验证错误的格式化输出

添加 _format_error 方法以更清晰地展示验证错误的详细信息，包括位置、类型、消息和输入值。当存在多个错误时，会为每个错误添加编号以提升可读性。

fastapi/exceptions.py

@@ -201,10 +201,50 @@ class ValidationException(Exception):
             context += f"\n    {self.endpoint_path}"
         return context
 
+    def _format_error(self, err: Any) -> str:
+        if not isinstance(err, dict):
+            return f"  {err}"
+        
+        loc = err.get("loc")
+        msg = err.get("msg")
+        error_type = err.get("type")
+        has_input = "input" in err
+        input_val = err.get("input")
+        
+        parts = []
+        
+        if loc:
+            if isinstance(loc, (list, tuple)):
+                loc_str = " -> ".join(str(item) for item in loc)
+            else:
+                loc_str = str(loc)
+            parts.append(f"  Loc: {loc_str}")
+        
+        if error_type:
+            parts.append(f"  Type: {error_type}")
+        
+        if msg:
+            parts.append(f"  Msg: {msg}")
+        
+        if has_input:
+            input_str = str(input_val)
+            if len(input_str) > 50:
+                input_str = input_str[:47] + "..."
+            parts.append(f"  Input: {input_str}")
+        
+        if not parts:
+            return f"  {err}"
+        
+        return "\n".join(parts)
+
     def __str__(self) -> str:
         message = f"{len(self._errors)} validation error{'s' if len(self._errors) != 1 else ''}:\n"
-        for err in self._errors:
-            message += f"  {err}\n"
+        for i, err in enumerate(self._errors):
+            if len(self._errors) > 1:
+                message += f"\nError {i + 1}:\n"
+            message += self._format_error(err)
+            if i < len(self._errors) - 1:
+                message += "\n"
         message += self._format_endpoint_context()
         return message.rstrip()