Error handling

Skill nexus-labs-automation/backend-observability/skills/error-handling

Capture errors with rich context for debugging and alertingFrom its SKILL.md

Install

npx -y skills add nexus-labs-automation/backend-observability --skill error-handling

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SKILL.md

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Error Handling

An error without context is useless. Every error should answer: What, Where, Who, When, Why.

Required Attributes

Attribute	Example	Required
`error.type`	ValidationError, TimeoutError	Yes
`error.message`	"Invalid email format"	Yes
`exception.stacktrace`	Full stack trace	Yes
`job.name`	checkout, signup	Recommended
`job.step`	payment, validation	Recommended

Error Classification

Level	Status	Action
Critical	500	Page immediately
Error	500	Alert, investigate
Warning	4xx	Track, batch review
Info	-	Log only

Structured Error Type

AppError {
  Type       string   // "validation", "timeout"
  Message    string   // Human-readable
  Code       string   // For grouping
  Retryable  bool     // Can retry?
  Context    map      // Additional context
}

Capture Pattern

On error:
  → Record error on span with error.type, job.name, job.step
  → Set span status to Error
  → Log structured error with trace_id
  → Increment error counter by type/job/step

Fingerprinting

Group by: error type + message (without dynamic data) + top stack frames

Strip from fingerprints: user IDs, request IDs, timestamps, tokens

Anti-Patterns

Swallowing errors → Log before returning default
Missing context → Add job.name, job.step, retry.count
PII in messages → Use structured attributes, not interpolation
No retry context → Include attempt count and will_retry

References

references/methodology/jtbd-for-backend.md
references/anti-patterns.md