type "fixes"

guardrails/functional/chain/guard.py

@@ -1,9 +1,9 @@
 import json
 from copy import deepcopy
-from typing import Dict, Optional, TypeVar
+from typing import Dict, Optional, TypeVar, cast
 
 from langchain_core.messages import BaseMessage
-from langchain_core.runnables.base import Runnable, RunnableConfig
+from langchain_core.runnables import Runnable, RunnableConfig
 
 from guardrails.errors import ValidationError
 from guardrails.functional.guard import Guard as FGuard
@@ -13,26 +13,31 @@
 
 class Guard(FGuard, Runnable):
     def invoke(self, input: T, config: Optional[RunnableConfig] = None) -> T:
-        output = deepcopy(input)
-        str_input = input
+        output = BaseMessage(content="", type="")
+        str_input = None
         input_is_chat_message = False
         if isinstance(input, BaseMessage):
             input_is_chat_message = True
-            str_input = input.content
+            str_input = str(input.content)
+            output = deepcopy(input)
+        else:
+            str_input = str(input)
 
         response = self.validate(str_input)
 
         validated_output = response.validated_output
         if not validated_output:
-            raise ValidationError((
-                "The response from the LLM failed validation!"
-                "See `guard.history` for more details."
-            ))
+            raise ValidationError(
+                (
+                    "The response from the LLM failed validation!"
+                    "See `guard.history` for more details."
+                )
+            )
 
         if isinstance(validated_output, Dict):
             validated_output = json.dumps(validated_output)
 
         if input_is_chat_message:
             output.content = validated_output
-            return output
-        return validated_output
+            return cast(T, output)
+        return cast(T, validated_output)