fix(core): replace lambda functions in with_structured_output to enable serialization issue #33128

[Rohanvasudev1]

Replaces non-serializable lambda functions with serializable class instances in with_structured_output method to fix LangGraph Studio thread deletion.

• Add SerializableParsingErrorHandler and SerializableNoneAssigner classes
• Replace lambda _: None functions in RunnablePassthrough.assign calls
• Maintains backward compatibility and identical functionality

[codspeed-hq]

CodSpeed Performance Report

Merging #33291 will not alter performance

_{Comparing Rohanvasudev1:origin/33128 (e22dc03) with master (90e4d94)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 13 untouched
⏩ 21 skipped¹

Footnotes

1. 21 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩