Errors swallowed to make it "work"
把错误吞掉，让它“能跑”
The agent wraps failing code in a catch that does nothing (or only logs) so the error disappears, and so does the signal that something is broken.
Applies to: Claude Code · Cursor · Codex · Copilot agent
Symptom
`catch (e) {}`, `except: pass`, `except Exception:` replacing a narrow handler, or a catch that returns `null` and lets bad data flow downstream.
Why it happens
A crash is a visible failure; a swallowed error makes the task look done and the test pass. agent-review lists AR017 (silent or swallowed catch) and AR019 (broad exception catch), noting agents widen catches to make tests pass when the real failure is upstream.
Example
From the agent-review taxonomy (AR017).
jstry { fn() } catch (e) { /* swallow */ }
Copy-paste fixes
Pick the files for the agents you use. Snippets are in English so they work in any repo.
Rules
Claude Code: add to CLAUDE.md
CLAUDE.md## Don't hide errors
- Never add an empty catch, `except: pass`, or a catch that only logs and continues, unless the user asked
for it and you comment why the error is safe to ignore.
- Catch the narrowest error type you can handle, and handle it (retry, fallback with a visible signal,
or rethrow with context).
- If an error appears while you work, find its cause. Do not wrap it to make it go away.
Rules
Codex, Copilot coding agent and others: add to AGENTS.md
AGENTS.md## Don't hide errors
- Never add an empty catch, `except: pass`, or a catch that only logs and continues, unless the user asked
for it and you comment why the error is safe to ignore.
- Catch the narrowest error type you can handle, and handle it (retry, fallback with a visible signal,
or rethrow with context).
- If an error appears while you work, find its cause. Do not wrap it to make it go away.
Cursor rule
Cursor: project rule
.cursor/rules/swallowed-error.mdc---
description: "AgentFails: Errors swallowed to make it 'work'"
alwaysApply: true
---
## Don't hide errors
- Never add an empty catch, `except: pass`, or a catch that only logs and continues, unless the user asked
for it and you comment why the error is safe to ignore.
- Catch the narrowest error type you can handle, and handle it (retry, fallback with a visible signal,
or rethrow with context).
- If an error appears while you work, find its cause. Do not wrap it to make it go away.
CI / script
Lint rules that catch it (ESLint / Ruff)
eslint.config.mjs / pyproject.toml// eslint.config.mjs
rules: { "no-empty": ["error", { allowEmptyCatch: false }] }
# pyproject.toml (ruff)
[tool.ruff.lint]
extend-select = ["E722", "BLE001", "S110"] # bare except, blind except, try-except-pass