Debugging Fundamentals: Reading Errors Like a Developer
What you will learn
- Read a stack trace and identify the exact file, line, and function where an error occurred
- Categorize common error types: syntax, runtime, type, and logic errors
- Write effective AI prompts for debugging that include context, not just the error message
- Use the scientific method for debugging: hypothesize, test, repeat
# Debugging Fundamentals: Reading Errors Like a Developer
The Number One Debugging Skill: Read the Error
Most beginners see an error and immediately panic or paste the entire message into a search engine. Senior developers read the error systematically:
TypeError: Cannot read properties of undefined (reading 'map')
at UserList (src/components/UserList.tsx:14:22)
at renderWithHooks (node_modules/react-dom/...)
at mountIndeterminateComponent (node_modules/react-dom/...)How to read this:
1. Error type: TypeError — you are trying to use something that does not exist
2. Message: Cannot read properties of undefined (reading 'map') — you called .map() on something that is undefined
3. Location: UserList.tsx:14:22 — line 14, column 22 of UserList.tsx
4. Stack trace: Shows the call chain that led to the error
The fix is almost always at the first line that references YOUR code (not node_modules). In this case: line 14 of UserList.tsx. Look there, find what is undefined, and figure out why.
Common Error Categories
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What you'll learn:
- Read a stack trace and identify the exact file, line, and function where an error occurred
- Categorize common error types: syntax, runtime, type, and logic errors
- Write effective AI prompts for debugging that include context, not just the error message