Fix · Node, npm and build

TypeError: Cannot read properties of undefined

What you may see

The page crashes with cannot read properties of undefined (reading 'x')
It works for some records and breaks for others

Most likely cause

The code reads a field of something that does not exist yet or is empty for this record.

Check first (about two minutes)

Read the name in "reading 'x'" and the file and line in the stack.

The fix prompt

What you type here never leaves your browser. The search runs on this page, and nothing is sent to a server or to an AI.

The exact error or what you see

What you did before it happened

Kept only in this browser, on this device. Keys and passwords are removed before anything is saved.

Prompt language

You are a patient senior engineer who knows Node.js, npm and build tools and explains them to people who are not developers. I am not a developer, so explain every step in plain words and tell me exactly which button, menu or command you mean. If you are not sure about something, say so; do not guess.

THE PROBLEM
TypeError: Cannot read properties of undefined

THE EXACT ERROR OR WHAT I SEE
[paste the exact error here]

WHAT I DID BEFORE IT HAPPENED
[write in a few words what you did before it happened]

MOST LIKELY CAUSE
The code reads a field of something that does not exist yet or is empty for this record.

DO THESE STEPS, IN THIS ORDER
1. Find the exact line and what object is undefined there.
2. Find out why it is empty: data not loaded yet, an empty record, or a wrong field name.
3. Handle the empty case properly (a loading state, an empty state, optional chaining) instead of hiding it.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- The page works with a normal record, an empty record and while loading.
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not add ? everywhere without understanding the cause.
- Anything I did not ask about: the design, the text, other pages, other settings or the data.
- Do not delete files, data or branches, do not reset or force-push, and do not rewrite history, unless you first show me exactly what would be lost and I say yes.
- Do not paste, print or ask me to paste a password or secret key into this chat. If one is needed, tell me which settings page of the right service to store it in.

WHEN YOU FINISH
Explain in simple words what you changed (file by file or setting by setting), why you changed it, and how I can undo it.

Paste it into Claude, ChatGPT, Gemini or Cursor, then follow what it says.

After you tried it, did it work?

Steps

Find the exact line and what object is undefined there.
Find out why it is empty: data not loaded yet, an empty record, or a wrong field name.
Handle the empty case properly (a loading state, an empty state, optional chaining) instead of hiding it.

Do not do this

Do not wrap the whole page in try/catch.
Do not add ? everywhere without understanding the cause.

Try another entry