Error Resolver

A first-principle approach to diagnosing and resolving errors across all languages and frameworks.

Core Philosophy

The 5-step Error Resolution Process:

1. CLASSIFY -> 2. PARSE -> 3. MATCH -> 4. ANALYZE -> 5. RESOLVE | | | | | What type? Extract key Known Root cause Fix + information pattern? analysis Prevent

Quick Start

When you encounter an error:

• Paste the full error (including stack trace if available)

• Provide context (what were you trying to do?)

• Share relevant code (the file/function involved)

Error Classification Framework

Primary Categories

Category Indicators Common Causes

Syntax Parse error, Unexpected token Typos, missing brackets, invalid syntax

Type TypeError, type mismatch Wrong data type, null/undefined access

Reference ReferenceError, NameError Undefined variable, scope issues

Runtime RuntimeError, Exception Logic errors, invalid operations

Network ECONNREFUSED, timeout, 4xx/5xx Connection issues, wrong URL, server down

Permission EACCES, PermissionError File/directory access, sudo needed

Dependency ModuleNotFound, Cannot find module Missing package, version mismatch

Configuration Config error, env missing Wrong settings, missing env vars

Database Connection refused, query error DB down, wrong credentials, bad query

Memory OOM, heap out of memory Memory leak, large data processing

Secondary Attributes

• Severity: Fatal / Error / Warning / Info

• Scope: Build-time / Runtime / Test-time

• Origin: User code / Framework / Third-party / System

Analysis Workflow

Step 1: Classify

Identify the error category by examining:

• Error name/code (e.g., ENOENT , TypeError )

• Error message keywords

• Where it occurred (compile, runtime, test)

Step 2: Parse

Extract key information:

• Error code: [specific code if any]
• File path: [where the error originated]
• Line number: [exact line if available]
• Function/method: [context of the error]
• Variable/value: [what was involved]
• Stack trace depth: [how deep is the call stack]

Step 3: Match Patterns

Check against known error patterns:

• See patterns/ directory for language-specific patterns

• Match error signatures to known solutions

• Check replay history for previous solutions

Step 4: Root Cause Analysis

Apply the 5 Whys technique:

Error: Cannot read property 'name' of undefined Why 1? -> user object is undefined Why 2? -> API call returned null Why 3? -> User ID doesn't exist in database Why 4? -> ID was from stale cache Why 5? -> Cache invalidation not implemented

Root Cause: Missing cache invalidation logic

Step 5: Resolve

Generate actionable solution:

• Immediate fix - Get it working now

• Proper fix - The right way to solve it

• Prevention - How to avoid in the future

Output Format

When resolving an error, provide:

Error Diagnosis

Classification: [Category] / [Severity] / [Scope]

Error Signature:

• Code: [error code]
• Type: [error type]
• Location: [file:line]

Root Cause

[Explanation of why this error occurred]

Contributing Factors:

1. [Factor 1]
2. [Factor 2]

Solution

Immediate Fix

[Quick steps to resolve]

Code Change

[Specific code to add/modify]

Verification

[How to verify the fix works]

Prevention

[How to prevent this error in the future]

Replay Tag

[Unique identifier for this solution - for future reference]

Replay System

The replay system records successful solutions for future reference.

Recording a Solution

After resolving an error, record it:

Create solution record in project

mkdir -p .claude/error-solutions

Solution file format: [error-type]-[hash].yaml

Solution Record Format

.claude/error-solutions/[error-signature].yaml

id: "nodejs-module-not-found-express" created: "2024-01-15T10:30:00Z" updated: "2024-01-20T14:22:00Z"

error: type: "dependency" category: "ModuleNotFound" language: "nodejs" pattern: "Cannot find module 'express'" context: "npm project, missing dependency"

diagnosis: root_cause: "Package not installed or node_modules corrupted" factors: - "Missing npm install after git clone" - "Corrupted node_modules directory" - "Package not in package.json"

solution: immediate: - "Run: npm install express" proper: - "Check package.json has express listed" - "Run: rm -rf node_modules && npm install" code_change: null

verification:

• "Run the application again"
• "Check express is in node_modules"

prevention:

• "Add npm install to project setup docs"
• "Use npm ci in CI/CD pipelines"

metadata: occurrences: 5 last_resolved: "2024-01-20T14:22:00Z" success_rate: 1.0 tags: ["nodejs", "npm", "dependency"]

Replay Lookup

When encountering an error:

• Generate error signature from the error message

• Search .claude/error-solutions/ for matching patterns

• If found, apply the recorded solution

• If new, proceed with full analysis and record the solution

Error Signature Generation

signature = hash( error_type + error_code + normalized_message + # remove specific values language + framework )

Example transformations:

• Cannot find module 'express' -> Cannot find module '{module}'

• TypeError: Cannot read property 'name' of undefined -> TypeError: Cannot read property '{prop}' of undefined

Debug Commands

Useful commands during debugging:

Node.js

Verbose error output

NODE_DEBUG=* node app.js

Memory debugging

node --inspect app.js

Check installed packages

npm ls [package-name]

Verify package.json

npm ls --depth=0

Python

Debug mode

python -m pdb script.py

Check installed packages

pip show [package-name] pip list

General

Check file permissions

ls -la [file]

Check port usage

lsof -i :[port] netstat -an | grep [port]

Check environment variables

env | grep [VAR_NAME] printenv [VAR_NAME]

Check disk space

df -h

Check memory

free -m # Linux vm_stat # macOS

Common Debugging Patterns

Pattern 1: Binary Search

When the error location is unclear:

• Comment out half the code

• If error persists, it's in the remaining half

• Repeat until you find the exact line

Pattern 2: Minimal Reproduction

Create the smallest code that reproduces the error:

• Start with empty file

• Add code piece by piece

• Stop when error appears

• That's your minimal repro case

Pattern 3: Rubber Duck Debugging

Explain the problem out loud (or to Claude):

• What should happen?

• What actually happens?

• What changed recently?

• What assumptions am I making?

Pattern 4: Git Bisect

Find which commit introduced the bug:

git bisect start git bisect bad # current commit is bad git bisect good [last-known-good-commit]

Git will checkout commits for you to test

git bisect good/bad # mark each as good or bad git bisect reset # when done

Reference Files

patterns/ - Language-specific error patterns

• nodejs.md

• Node.js common errors

• python.md

• Python common errors

• react.md

• React/Next.js errors

• database.md

• Database errors

• docker.md

• Docker/container errors

• git.md

• Git errors

• network.md

• Network/API errors

analysis/ - Analysis methodologies

• stack-trace.md

• Stack trace parsing guide

• root-cause.md

• Root cause analysis techniques

replay/ - Replay system

• solution-template.yaml
• Template for recording solutions