fix: replace bare except clauses with proper exception handling

[javascp]

• Replace bare 'except:' with 'except Exception:' in writer.py and operators.py to avoid catching system-level exceptions like KeyboardInterrupt
• Use specific exceptions (IndexError, ValueError) in rec_postprocess.py where only character index lookup failures are expected

This change improves code robustness and follows Python best practices for exception handling without changing any runtime behavior.

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