Update unit tests to catch up with langchain-core (#743)

Updating the unit tests to catch up with langchain-core. No adjustements
should be necessary to user code, the issues manifest themselves only with the
given test set up (e.g., snapshots). langchain-core changes were either
additive or self-consistent.

langserve/api_handler.py

@@ -29,6 +29,7 @@
 from fastapi.exceptions import RequestValidationError
 from langchain_core._api.beta_decorator import warn_beta
 from langchain_core.callbacks.base import AsyncCallbackHandler
+from langchain_core.callbacks.manager import BaseCallbackManager
 from langchain_core.load.serializable import Serializable
 from langchain_core.runnables import Runnable, RunnableConfig
 from langchain_core.runnables.config import (
@@ -470,7 +471,12 @@ def _add_callbacks(
     """Add the callback aggregator to the config."""
     if "callbacks" not in config:
         config["callbacks"] = []
-    config["callbacks"].extend(callbacks)
+    if "callbacks" in config:
+        if isinstance(config["callbacks"], list):
+            config["callbacks"].extend(callbacks)
+        elif isinstance(config["callbacks"], BaseCallbackManager):
+            for callback in callbacks:
+                config["callbacks"].add_handler(callback, inherit=True)
 
 
 _MODEL_REGISTRY = {}

langserve/client.py

@@ -431,11 +431,15 @@ def batch(
         self,
         inputs: List[Input],
         config: Optional[RunnableConfig] = None,
+        *,
+        return_exceptions: bool = False,
         **kwargs: Any,
     ) -> List[Output]:
         if kwargs:
-            raise NotImplementedError("kwargs not implemented yet.")
-        return self._batch_with_config(self._batch, inputs, config)
+            raise NotImplementedError(f"kwargs not implemented yet. Got {kwargs}")
+        return self._batch_with_config(
+            self._batch, inputs, config, return_exceptions=return_exceptions
+        )
 
     async def _abatch(
         self,