Raise ValueError if .with_structured_output is called with an unsuppo…

…rted model (langchain-ai#323)

libs/aws/langchain_aws/chat_models/bedrock.py

@@ -805,7 +805,7 @@ class AnswerWithJustification(BaseModel):
                 schema, include_raw=include_raw, **kwargs
             )
         if "claude-3" not in self._get_model():
-            ValueError(
+            raise ValueError(
                 f"Structured output is not supported for model {self._get_model()}"
             )