Honor falsey except fallbacks in python wrangle and emit concise error context

[Copilot]

python wrangle failures were still raising when except was set to a falsey value (e.g. {}), which blocked the intended offline-debugging flow. This change makes fallback behavior consistent for all explicit except values and surfaces a compact error signal in logs.

• Fallback semantics in python wrangle

  • Switch exception-fallback guard from truthiness to explicit presence (is not None).
  • except now works for values like {}, 0, false, and "" instead of being ignored.

• Debuggability on caught exceptions

  • When fallback is used, log a concise message including exception type/message and that except output is being returned.

• Regression coverage

  • Add a focused recipe test for object fallback (except: {}) to prevent reintroducing falsey-handling regressions.

wrangles:
  - python:
      input: attributes_json
      output: attributes_dict
      command: {item.get('key'): item.get('value') for item in attributes_json if isinstance(item, dict) and item.get('key')}
      except: {}

[ebhills]

Queue triage (2026-07-27)

• Disposition: Draft — delivery-owner action
• Delivery owner: @ebhills
• Next action: Human sponsor is @ebhills. Keep this bot-authored work Draft until CI runs, overlap with current exception/error work is checked, and a primary reviewer other than the delivery owner is selected.

GitHub is the status record; update this PR rather than the external spreadsheet.