Paste the error message, code, or scenario in place of {{args}} to get targeted debugging help and solutions.

Debug Error

Please help diagnose and fix the following error:

{{args}}

Diagnostic Process

1. Error Analysis

Understand the Error

• What is the error message?
• What type of error is it? (Syntax, Runtime, Logic, Type, Reference, etc.)
• When does it occur? (Compile-time, Runtime, specific conditions)
• What is the stack trace showing?

Identify the Source

• Which file and line number?
• Which function/method is failing?
• What was the execution path leading to the error?

2. Context Investigation

Code Context

Analyze the code around the error:
- What is this code trying to do?
- What are the inputs at the time of error?
- What are the variable states?
- Are there any assumptions being made?

Environment Context

• What environment? (Development, Staging, Production)
• Browser/Node version?
• Operating system?
• Dependencies and versions?

User Context

• What action triggered the error?
• Can it be reproduced consistently?
• Does it happen for all users or specific ones?
• What are the reproduction steps?

3. Root Cause Analysis

Common Error Patterns

Null/Undefined Errors

// Error: Cannot read property 'x' of undefined
// Cause: Variable is undefined/null
// Fix: Add null checks
if (obj && obj.x) {
  // Use obj.x
}

Type Errors

// Error: arr.map is not a function
// Cause: Variable is not an array
// Fix: Validate type
if (Array.isArray(arr)) {
  arr.map(...)
}

Async Errors

// Error: Promise rejection unhandled
// Cause: Missing error handling
// Fix: Add try-catch or .catch()
try {
  await asyncFunction();
} catch (error) {
  handleError(error);
}

Scope Errors

// Error: Variable not defined
// Cause: Variable out of scope or not declared
// Fix: Declare variable or adjust scope

Off-by-One Errors

// Error: Index out of bounds
// Cause: Loop condition incorrect
// Fix: Check array.length - 1
for (let i = 0; i < arr.length; i++) { // not <=
  // Use arr[i]
}

4. Common Error Types & Solutions

JavaScript/TypeScript Errors

ReferenceError

• Variable not declared
• Accessing before declaration
• Typo in variable name

TypeError

• Calling undefined as function
• Accessing property of null/undefined
• Wrong type passed to function

SyntaxError

• Missing brackets/parentheses
• Invalid syntax
• Import/export issues

RangeError

• Invalid array length
• Number out of range
• Stack overflow (recursion)

Network/API Errors

404 Not Found

• Wrong endpoint URL
• Resource doesn't exist
• Routing issue

CORS Error

• Cross-origin request blocked
• Missing CORS headers
• Incorrect origin configuration

Timeout

• Request taking too long
• Network issues
• Server not responding

401/403 Errors

• Authentication failed
• Missing token
• Insufficient permissions

5. Debugging Steps

Step 1: Reproduce the Error

1. Identify exact steps to trigger error
2. Note any specific conditions
3. Try in different environments

Step 2: Isolate the Problem

1. Add console.logs/debugger statements
2. Check variable values before error
3. Verify function inputs
4. Test in isolation

Step 3: Form Hypothesis

1. What do you think is causing it?
2. Why does it fail under these conditions?
3. What would fix it?

Step 4: Test the Fix

1. Apply potential fix
2. Verify error is resolved
3. Check for side effects
4. Test edge cases

Step 5: Prevent Recurrence

1. Add error handling
2. Add input validation
3. Add tests for this scenario
4. Add logging/monitoring

6. Debug Code Examples

Add Defensive Checks

// Before (error-prone)
function process(data) {
  return data.items.map(item => item.value);
}

// After (defensive)
function process(data) {
  if (!data || !Array.isArray(data.items)) {
    console.error('Invalid data format:', data);
    return [];
  }

  return data.items
    .filter(item => item && typeof item.value !== 'undefined')
    .map(item => item.value);
}

Add Try-Catch

// Before
async function fetchData() {
  const response = await fetch(url);
  return response.json();
}

// After
async function fetchData() {
  try {
    const response = await fetch(url);
    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }
    return await response.json();
  } catch (error) {
    console.error('Failed to fetch data:', error);
    throw error; // or return default value
  }
}

Add Logging

function complexCalculation(a, b, c) {
  console.log('Input:', { a, b, c });

  const step1 = a * b;
  console.log('After step1:', step1);

  const step2 = step1 + c;
  console.log('After step2:', step2);

  const result = step2 / (a + b);
  console.log('Final result:', result);

  return result;
}

7. Output Format

Provide the following:

1. Error Diagnosis

• What the error means
• Why it's occurring
• Root cause analysis

2. Immediate Fix

• Code changes needed
• Step-by-step fix instructions
• Fixed code example

3. Prevention

• How to prevent this error
• Validation to add
• Tests to write

4. Additional Recommendations

• Related issues to check
• Code improvements
• Best practices to follow

5. Debugging Tips

• How to debug similar issues
• Tools to use
• Logging strategies

Generate a complete error analysis and solution following this structure.