codesandbox / codesandbox/codesandbox-client

Strange TypeScript error: Cannot read properties of undefined

Open
#7,301 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

🐛 Bug
Dominant language
JavaScript
Stars
13.6k
Forks
2.4k
Avg merge
6d 19h
Merged PRs (30d)
2

Description

🐛 bug report

Preflight Checklist

  • I have read the Contributing Guidelines for this project.
  • I agree to follow the Code of Conduct that this project
    adheres to.
  • I have searched the issue tracker for an issue that matches the one I want
    to file, without success.

Description of the problem

As the title states, I see this TypeScript error in CodeSandbox, which isn't reproducible in TS Playground: https://www.typescriptlang.org/play?ssl=5&ssc=3&pln=1&pc=1#code/KYDwDg9gTgLgBDAnmYcCqBnYARCBjAVwFtgA7GAFQEsYAbYAYQAsBDUgc2AHkwYqJSGOAF44AbwBQcOADMqUDJRr0A-AC44iqFQ4BuKZuB4BAE2p1g6zTG16DOmMCgA3FrSuliAIyf6AvvoGoJCwcMaC8ARYuIQk5Ob0zGycAKIyMkbwogAUktJyCkoWInAARAASwLS0EKUANAZY4WbKqKKlAOrQtCYAhPX25E6utCUAjAAMUxJ+Gpg4+MRkRYmsHNy8-IIAlCIAfOIS4RgQ9AB0NezZAOQ0cADu0ADWGNfbM7pAA

I also don't get the error in my local Visual Studio Code.

How has this issue affected you? What are you trying to accomplish?

I'd like to set default values for properties passed to my hook. Somehow TypeScript in the CodeSandbox environment doesn't like that syntax even though it is valid TypeScript. Not sure what is going on.

To Reproduce

See this sandbox:

Link to sandbox: https://codesandbox.io/s/newline-custom-react-hooks-with-typescript-5rcdvu?file=/src/hooks/useDocumentTitleChangeEffect.ts
Your Environment
Software Name/Version
Сodesandbox 2bfc25146
Browser Chrome
Operating System macOS

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Open the linked CodeSandbox and inspect src/hooks/useDocumentTitleChangeEffect.ts, then compare its TypeScript setup with the provided TypeScript Playground and local Visual Studio Code behavior. Reproduce the error and identify the environment difference; done means the valid default-property syntax no longer produces the unexpected error in CodeSandbox.

Written by the indexing model from the issue text.

Assessment

Tech stack
react, typescript
Domain
developer-experience, tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.