fix(stream): prevent ERR_INVALID_STATE when pushing to closed stream#1894
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GdMacmillan wants to merge 5 commits intolangchain-ai:mainfrom
Open
fix(stream): prevent ERR_INVALID_STATE when pushing to closed stream#1894GdMacmillan wants to merge 5 commits intolangchain-ai:mainfrom
GdMacmillan wants to merge 5 commits intolangchain-ai:mainfrom
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Add a guard check in IterableReadableWritableStream.push() to verify the stream is not closed before attempting to enqueue data. This prevents the "Controller is already closed" TypeError that occurs when StreamMessagesHandler tries to emit tokens after the stream consumer has completed. Fixes langchain-ai#1837 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
Add a guard check in
IterableReadableWritableStream.push()to verify the stream is not closed before attempting to enqueue data.Problem
When using
graph.stream()withstreamMode: ['messages'], aTypeError [ERR_INVALID_STATE]: Invalid state: Controller is already closedoccurs if the stream consumer completes before the LLM finishes generating tokens.This happens because
IterableReadableWritableStream.push()doesn't check the_closedflag before callingcontroller.enqueue().Solution
Add a simple guard:
if (this._closed) return;at the start of thepush()method.The
_closedflag already exists and is set by theclose()method - it just wasn't being checked inpush().Testing
Fixes #1837