# Debugging

> Systematic debugging and troubleshooting of code issues, analyzing error messages, and finding root causes. Use when this capability is needed.

- Skill: `tomevault-io/debugging-2` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/debugging-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/debugging-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/debugging-2

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# Debugging Skill

## When to use this skill

Use this skill when the user:
- Reports a bug or error
- Shares an error message or stack trace
- Needs help understanding why code isn't working
- Wants to fix a runtime issue

## Debugging Methodology

### 1. Gather Information
- What is the expected behavior?
- What is the actual behavior?
- When did the issue start?
- Can it be reproduced consistently?

### 2. Analyze the Error
- Parse error messages and stack traces
- Identify the error type and location
- Understand the execution flow that led to the error

### 3. Form Hypotheses
- List possible causes based on the error
- Prioritize by likelihood
- Consider recent changes

### 4. Investigate
- Examine relevant code sections
- Check variable values and state
- Review related components

### 5. Propose Solutions
- Suggest fixes for the root cause
- Explain why the fix works
- Consider side effects

## Common Error Patterns

### Null/Undefined Errors
- Check for uninitialized variables
- Verify function return values
- Add null checks where needed

### Type Errors
- Verify data types match expectations
- Check type conversions
- Review function signatures

### Logic Errors
- Trace execution flow step by step
- Check conditional statements
- Verify loop boundaries

### Concurrency Issues
- Look for race conditions
- Check lock ordering
- Review shared state access

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