fix: narrow bare excepts around json.loads in python_executor

[harshadkhetpal]

Summary

Two bare except: clauses in LightAgent/builtin_tools/python_executor.py wrap json.loads fallbacks (ruff E722). A bare except also swallows KeyboardInterrupt / SystemExit and can mask unrelated bugs in the recursive code-cleaning path. Narrowed both to the exceptions json.loads actually raises:

except (json.JSONDecodeError, TypeError):

Behavior for malformed JSON input is unchanged — only the accidental swallowing of process-control exceptions is removed.

Testing

python -m py_compile passes; ruff check --select E722 on the file goes from 2 errors to clean.

🤖 Generated with Claude Code

[wxai-space]

Changes requested

The intent to narrow the bare except blocks is correct, but the second change introduces a compatibility regression.

A deeply nested JSON string that currently falls back to a normal code string now raises RecursionError from json.loads(), which can abort a tool call. I reproduced this with a 2,000-level nested JSON value: main returns a string, while this PR raises RecursionError.

Please isolate the json.loads() calls from the subsequent recursive cleanup and catch parsing failures appropriate for untrusted model output, including RecursionError where the existing fail-soft behavior is intended. Exceptions from unrelated cleanup logic should remain visible.

Please add regression tests for malformed JSON, deeply nested JSON, nested code fields, and propagation of KeyboardInterrupt/SystemExit. The full local suite passes, but it does not cover _clean_code_string().