Objective
Your mission
Create or find 4 errors (one of each type), read the messages, and identify type, message, location, and variable involved. Output: error_reading_log.md.
You need: Any AI coding tool with console/dev tools.
Time: 25 minutes.
Step 1: learn the 4 error types (5 min)
1. Syntax Errors — code is malformed (missing bracket, typo):
SyntaxError: Unexpected token '}'
Look for: "Syntax" or "Parse," line number, unexpected token.
2. Runtime Errors — code runs but fails (undefined, not defined):
TypeError: Cannot read properties of undefined (reading 'map')
ReferenceError: supabase is not defined
Look for: type (TypeError, ReferenceError), specific message, variable name. Very common in AI code.
3. Logic Errors — no error message, but wrong result: The tip calculator shows $10/person instead of $30. No crash — just wrong math. Hardest to catch.
4. Deployment Errors — works locally, fails deployed:
Error: Environment variable not found: API_KEY
Build failed: Module not found
Look for: "Build," "Environment," HTTP status codes (404, 500).
When reading any error, focus on:
- Error type (TypeError, SyntaxError) — the category
- Specific message — what went wrong
- File and line number — where it happened
- Variable/function name — what was involved
Ignore: The stack trace (long list of function calls). The AI can read it.
The error message is your prediction input
Knowing the four types helps you make better predictions. 'TypeError: Cannot read properties of undefined (reading map)' → runtime error, code tried to .map() over something undefined, probably a data loading timing issue. Better prediction → faster debugging → better debugging instinct.
Step 2: build or open a project (2 min)
Build something with AI or use an existing project.
Step 3: create/find 4 errors (15 min)
Create one error of each type:
Syntax: Break a bracket or comma in the code. Remove a } or add an extra {.
Runtime: Reference an undefined variable. Change a variable name so it doesn't match the import.
Logic: Change a calculation to be wrong. Multiply instead of divide, or sort ascending instead of descending.
Deployment: Remove an environment variable (if applicable) or note why deployment errors aren't applicable to your setup.
For each error:
- Read the error message
- Identify: type, specific message, file/line, variable involved
- Write your prediction ("I think the error is because...")
- Paste to AI and compare
Write in your file:
## Error 1: Syntax
Error message: [full message]
Type: [syntax/runtime/logic/deployment]
Specific message: [what went wrong]
File/line: [location]
Variable involved: [name]
My prediction: "I think the error is because..."
AI's diagnosis: [summary]
Comparison: [right/wrong/close]
## Error 2: Runtime
[same structure]
## Error 3: Logic
[same structure]
## Error 4: Deployment
[same structure — or note why not applicable]
The tip calculator shows $10 per person instead of $30, and there's no error in the console. What type of error is it?
No crash, just a wrong result: a logic error, the hardest kind to catch because nothing tells you it happened.