community[patch]: Add safe lookup to OpenAI response adapter (#14765)

## Description
Similar to #5861, I've
experienced `KeyError`s resulting from unsafe lookups in the
`convert_dict_to_message` function in [this
file](https://github.com/langchain-ai/langchain/blob/master/libs/community/langchain_community/adapters/openai.py).
While that issue focused on `KeyError 'content'`, I've opened another
issue (#14764) about how the problem still exists in the same function
but with `KeyError 'role'`. The fix for #5861 only added a safe lookup
to the specific line that was giving them trouble.. This PR fixes the
unsafe lookup in the rest of the function but the problem still exists
across the repo.

## Issues
* #14764
* #5861 

## Dependencies
* None

## Checklist
[x] make format
[x] make lint
[ ] make test - Results in `make: *** No rule to make target 'test'.
Stop.`

## Maintainers
* @hinthornw

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/adapters/openai.py

@@ -71,34 +71,34 @@ def convert_dict_to_message(_dict: Mapping[str, Any]) -> BaseMessage:
     Returns:
         The LangChain message.
     """
-    role = _dict["role"]
+    role = _dict.get("role")
     if role == "user":
-        return HumanMessage(content=_dict["content"])
+        return HumanMessage(content=_dict.get("content", ""))
     elif role == "assistant":
         # Fix for azure
         # Also OpenAI returns None for tool invocations
         content = _dict.get("content", "") or ""
         additional_kwargs: Dict = {}
-        if _dict.get("function_call"):
-            additional_kwargs["function_call"] = dict(_dict["function_call"])
-        if _dict.get("tool_calls"):
-            additional_kwargs["tool_calls"] = _dict["tool_calls"]
+        if function_call := _dict.get("function_call"):
+            additional_kwargs["function_call"] = dict(function_call)
+        if tool_calls := _dict.get("tool_calls"):
+            additional_kwargs["tool_calls"] = tool_calls
         return AIMessage(content=content, additional_kwargs=additional_kwargs)
     elif role == "system":
-        return SystemMessage(content=_dict["content"])
+        return SystemMessage(content=_dict.get("content", ""))
     elif role == "function":
-        return FunctionMessage(content=_dict["content"], name=_dict["name"])
+        return FunctionMessage(content=_dict.get("content", ""), name=_dict.get("name"))
     elif role == "tool":
         additional_kwargs = {}
         if "name" in _dict:
             additional_kwargs["name"] = _dict["name"]
         return ToolMessage(
-            content=_dict["content"],
-            tool_call_id=_dict["tool_call_id"],
+            content=_dict.get("content", ""),
+            tool_call_id=_dict.get("tool_call_id"),
             additional_kwargs=additional_kwargs,
         )
     else:
-        return ChatMessage(content=_dict["content"], role=role)
+        return ChatMessage(content=_dict.get("content", ""), role=role)
 
 
 def convert_message_to_dict(message: BaseMessage) -> dict: