fix(langgraph): Fix behavior around array return values from nodes (#… #2079

Job	Run time
Check formatting	1m 19s
check-readmes-synced	3s
Build	1m 43s
Check linting	1m 40s
Unit Tests (ubuntu-latest, 18.x)	1m 30s
validate-new-notebooks	4s
Unit Tests (ubuntu-latest, 20.x)	1m 25s
Validate Deno and Node dependencies in sync	6s
Unit Tests (ubuntu-latest, 22.4.1)	2m 12s
Unit Tests (windows-latest, 22.4.1)	3m 30s
Unit Tests (macos-latest, 22.4.1)	1m 37s
	15m 9s

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