| name | null-as-error-cc |
| description | Audit an Effect codebase for silent error swallowing -- catchAll patterns that collapse errors into sentinel values (null, [], false, void) in the success channel. Runs a scanner script, spawns a read-only auditor, and produces a classified report. NOT for: non-Effect projects, React/frontend code, plain TypeScript without Effect.
|
| allowed-tools | ["Read","Glob","Grep","Bash","Agent"] |
null-as-error
Detect silent error swallowing in Effect codebases. The antipattern:
catchAll(() => Effect.succeed(null)) collapses real errors (disk full, permissions)
into sentinel values (null, [], false) that callers cannot distinguish from
normal absence.
Project context
- effect_posture: !
~/.claude/skills/null-as-error-cc/scripts/probe-effect.sh
Workflow
Phase 1 -- Gate on Effect
If the probe above shows effect="false", stop immediately:
This project does not use Effect. The null-as-error scanner targets Effect-specific
patterns (catchAll, Effect.succeed, Effect.ignore). Nothing to scan.
Phase 2 -- Run scanner
Execute the scanner script. The user may provide a scope (directory path) as an argument;
default to src/.
bun ~/.claude/skills/null-as-error-cc/scripts/scan.ts [scope] --json
Capture the JSON output. If meta.hitsFound is 0:
No silent error swallowing patterns found in [scope]. Clean.
Stop here.
Phase 3 -- Semantic analysis
The scanner found hits. Spawn the auditor subagent to classify each one:
Agent({
subagent_type: "null-as-error-auditor",
prompt: <see below>
})
The auditor task prompt must include:
- The full scanner JSON output
- Reference file paths for the auditor to read:
~/.claude/skills/null-as-error-cc/references/patterns.md~/.claude/skills/null-as-error-cc/references/fixes.md~/.claude/skills/null-as-error-cc/references/guardrails.md
Phase 4 -- Report
Synthesize the auditor's findings into a final report:
## Silent Error Swallowing Audit
### Summary
- Scanned: N files in [scope]
- Found: N occurrences
- Breakdown: X errors, Y warnings, Z info, W suppressed
### Findings
#### [ERROR] ...
#### [WARNING] ...
#### [INFO] ...
#### [SUPPRESSED] ...
### Summary Table
| Function | File | Severity | Sentinel | Fix | Blast Radius |
|----------|------|----------|----------|-----|--------------|
Reference navigation
| Question | Load |
|---|
| Detection patterns and severity rules | references/patterns.md |
| Fix strategies and decision tree | references/fixes.md |
| False-positive prevention | references/guardrails.md |
| Auditor agent definition | ~/.claude/agents/null-as-error-auditor.md |
