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4.6

The Debugger

Estimated time: 25 minTool: VS Code, Claude Desktop
After this drill, you can:

After this drill, you have a systematic process for diagnosing and fixing errors — using AI to translate error messages and find root causes.

Why this matters

Errors are not failures. They are navigation. Every error message is precise communication from the computer about what went wrong and where. The problem is that error messages are written for compilers, not for humans. AI is excellent at translating error messages into actionable diagnoses. This drill teaches the three-step debugging process: read → translate → fix.

How to do it

  1. 1

    Introduce a deliberate error into your app

    In a component file, delete one closing bracket } or add a typo in a variable name. Save the file. The terminal or browser should show an error.

  2. 2

    Copy the full error message

    Copy everything: the error name, the file path, the line number, the stack trace. Do not try to interpret it first.

  3. 3

    Use the error translation prompt

    Paste the error into Claude Desktop. Ask for plain-language translation and the most likely fix.

  4. 4

    Apply the fix and verify the error is gone

    Make the suggested change. Save. Confirm the error disappears. If it doesn't, paste the new error into Claude and continue.

The prompt

PROMPT — Translate and Fix an ErrorModel: Claude Desktop
I have an error in my web application. Here is the complete error message:

[PASTE THE FULL ERROR MESSAGE — including file path and line number]

Please:
1. Translate this error into plain language: what exactly went wrong?
2. Where in my code is the problem? (quote the file and line)
3. What is the most likely fix?
4. Is there anything else in my project that might also need to change?

Success criteria

  • ✓You deliberately introduced an error and saw the error message
  • ✓You used Claude to translate the error into plain language
  • ✓You fixed the error following the AI guidance
  • ✓You can describe what caused the error in your own words

Common mistakes

Copying only part of the error message

→ The file path and line number are the most important parts. Without them, AI can only guess. Always copy the full message from the beginning.

Panicking instead of reading the error

→ Read the first line of the error message out loud. It usually tells you exactly what happened. 'Cannot read properties of undefined' — something is undefined. Find the undefined thing.