fix: add _parse_json_body_optional for callback failure API

Author: bchampp

src/aws_durable_execution_sdk_python_testing/web/handlers.py

@@ -81,25 +81,16 @@ def handle(self, parsed_route: Route, request: HTTPRequest) -> HTTPResponse:
             HTTPResponse: The HTTP response to send to the client
         """
 
-    def _parse_json_body(
-        self, request: HTTPRequest, required: bool = True
-    ) -> dict[str, Any]:
-        """Parse JSON body from HTTP request with validation.
-
-        Args:
-            request: The HTTP request containing the JSON body
-            required: Whether the request body is required
-
-        Returns:
-            dict: The parsed JSON data, or empty dict if not required and missing
+    def _parse_json_body(self, request: HTTPRequest) -> dict[str, Any]:
+        """Required body: raise if missing or invalid."""
+        if not request.body:
+            msg = "Request body is required"
+            raise InvalidParameterValueException(msg)
+        return self._parse_json_body_optional(request)
 
-        Raises:
-            InvalidParameterValueException: If the request body is required but empty or invalid JSON
-        """
+    def _parse_json_body_optional(self, request: HTTPRequest) -> dict[str, Any]:
+        """Optional body: return empty dict when missing, still raise on invalid JSON."""
         if not request.body:
-            if required:
-                msg = "Request body is required"
-                raise InvalidParameterValueException(msg)
             return {}
 
         # Handle both dict and bytes body types
@@ -695,7 +686,7 @@ def handle(self, parsed_route: Route, request: HTTPRequest) -> HTTPResponse:
             callback_route = cast(CallbackFailureRoute, parsed_route)
             callback_id: str = callback_route.callback_id
 
-            body_data: dict[str, Any] = self._parse_json_body(request, required=False)
+            body_data: dict[str, Any] = self._parse_json_body_optional(request)
             callback_request: SendDurableExecutionCallbackFailureRequest = (
                 SendDurableExecutionCallbackFailureRequest.from_dict(
                     body_data, callback_id