List index out of range _parse_chat_history_gemini

[jpaodev]

I'm getting the following error in file https://github.com/langchain-ai/langchain-google/blob/main/libs/vertexai/langchain_google_vertexai/chat_models.py

    input = context.run(step.invoke, input, config)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_core/runnables/base.py", line 5440, in invoke
    return self.bound.invoke(
           ^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 331, in invoke
    self.generate_prompt(
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 894, in generate_prompt
    return self.generate(prompt_messages, stop=stop, callbacks=callbacks, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 719, in generate
    self._generate_with_cache(
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 960, in _generate_with_cache
    result = self._generate(
             ^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_google_vertexai/chat_models.py", line 1374, in _generate
    return self._generate_gemini(
           ^^^^^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_google_vertexai/chat_models.py", line 1609, in _generate_gemini
    request = self._prepare_request_gemini(messages=messages, stop=stop, **kwargs)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_google_vertexai/chat_models.py", line 1464, in _prepare_request_gemini
    system_instruction, contents = _parse_chat_history_gemini(
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/users/user/project/.venv/lib/python3.11/site-packages/langchain_google_vertexai/chat_models.py", line 432, in _parse_chat_history_gemini
    content = parsed_content[0]
              ~~~~~~~~~~~~~~^^^
IndexError: list index out of range
During task with name 'agent' and id '843160a3-cf5c-da4f-13e9-db8b673e916b'

A safety check should be in place, e.g. parsed_content[0] if parsed_content else {"content": ""}

[lkuligin]

could you share a reproducible snippet, please?

[jpaodev]

@lkuligin

from datetime import datetime, timezone

from langchain_core.prompts import ChatPromptTemplate
# ....

from typing import Annotated, Any, Dict, List, Union
from typing_extensions import TypedDict

from langgraph.graph import StateGraph, START
from langgraph.graph.message import add_messages
from langgraph.prebuilt import ToolNode, tools_condition
from app.llm.base import llm_handler, llm
# ...
from langgraph.prebuilt import create_react_agent

class State(TypedDict):
    messages: Annotated[list, add_messages]
    selected_tools: list[str]
    tree: dict[str, Any]

class RepoAgent:
    def __init__(self, handler: Union[TestHandler, TestHandler2], branch: str | None = None, system_message: str | None = None):
        self.handler = handler
        self.branch = branch
        self.system_message = system_message
        self.agent = self.get_repo_agent()
        
    def get_repo_agent(self):
        if not llm:
            raise ValueError("LLM not initialized")
        
        builder = StateGraph(State)

        tools = get_repo_agent_tools(self.handler, self.branch)
        if not self.handler.project:
            raise ValueError("No Project has been provided.")
        
        def fetch_tree(state: State):
            return state
        
        def agent(state: State):
            # Map tool IDs to actual tools
            # based on the state's selected_tools list.
            if not llm:
                raise ValueError("LLM not initialized")
            selected_tools = tools
            # Bind the selected tools to the LLM for the current interaction.
            llm_with_tools = llm.bind_tools(selected_tools)
            # Invoke the LLM with the current messages and return the updated message list.
            return {"messages": [llm_with_tools.invoke(state["messages"], config={"callbacks": [CostCallbackHandler(self.handler.usage_information)]})]}


        pb_react_agent = create_react_agent(llm, tools=tools, prompt=self.system_message)
        builder.add_node("agent", agent)

        builder.add_edge(START, "fetch_tree")
        builder.add_node("fetch_tree", fetch_tree)
        builder.add_node("pb_agent", pb_react_agent)
        builder.add_edge("fetch_tree", "pb_agent")
        
        graph = builder.compile()
        return graph

    def get_agent(self):
        return self.agent

This was the example code snippet that was failing for me, thanks a lot!