Stream error

[NickGator1]

I am trying to run open-canvas locally, with Langgraph Studio. The page starts as expected, and the authentication via Supabase works, but when I enter a message, I always get this error (found in Langsmith logs):

`
InvalidUpdateError("Must write to at least one of ['changeme']")Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/init.py", line 1538, in astream
async for _ in runner.atick(

File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/runner.py", line 132, in atick
await arun_with_retry(t, retry_policy, stream=self.use_astream)

File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/retry.py", line 99, in arun_with_retry
async for _ in task.proc.astream(task.input, config):

File "/usr/local/lib/python3.11/site-packages/langchain_core/runnables/base.py", line 1018, in astream
yield await self.ainvoke(input, config, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/langgraph/utils/runnable.py", line 224, in ainvoke
ret = await asyncio.create_task(coro, context=context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/write.py", line 99, in _awrite
self.do_write(

File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/write.py", line 138, in do_write
raise InvalidUpdateError(

langgraph.errors.InvalidUpdateError: Must write to at least one of ['changeme']
`

The open-canvas code hasn't been edited, aside from the .env file and changing the constants.js file to point to the correct LANGGRAPH_API_URL.
I have langgraph 0.2.42, and langchain 0.3.6 versions

Here is my .env file:

# LangSmith tracing
LANGCHAIN_TRACING_V2=true
LANGCHAIN_API_KEY="< LANGCHAIN_API_KEY >"

# LLM API keys
# Anthropic used for reflection
ANTHROPIC_API_KEY="< ANTHROPIC_API_KEY >"
# OpenAI used for content generation
OPENAI_API_KEY="< OPENAI_API_KEY >"
# Optional, only required if using `Gemini 1.5 Flash` as the model.
# GOOGLE_API_KEY=

# Feature flags for hiding/showing specific models
NEXT_PUBLIC_FIREWORKS_ENABLED=true
# Gemini has some tool call streaming issues atm.
NEXT_PUBLIC_GEMINI_ENABLED=false
NEXT_PUBLIC_ANTHROPIC_ENABLED=true
NEXT_PUBLIC_OPENAI_ENABLED=true

# LangGraph Deployment, or local development server via LangGraph Studio.
# If running locally, this URL should be set in the `constants.ts` file.
# LANGGRAPH_API_URL=

# Supabase for authentication
# Public keys
NEXT_PUBLIC_SUPABASE_URL="< NEXT_PUBLIC_SUPABASE_URL >"
NEXT_PUBLIC_SUPABASE_ANON_KEY="< NEXT_PUBLIC_SUPABASE_ANON_KEY >"

Any suggestions on what could be causing this? Could it be misconfiguration of LangGraph Studio itself?