Cypress fails to start if tsconfig contains `"allowImportingTsExtensions": true`

[sapphi-red]

Current behavior

If the directory has Cypress and TypeScript 4.9 and the tsconfig.json in the parent directory has "allowImportingTsExtensions": true, Cypress outputs the following message and hangs forever.

> cypress-test-tiny@1.0.0 cypress:run
> cypress run

DevTools listening on ws://127.0.0.1:59272/devtools/browser/149879ae-3731-4086-862e-972b8c2e2999   

node:internal/process/esm_loader:40
      internalBinding('errors').triggerUncaughtException(
                                ^
[Object: null prototype] {
  [Symbol(nodejs.util.inspect.custom)]: [Function: [nodejs.util.inspect.custom]]
}

Desired behavior

Cypress doesn't hang and either of:

1. Shows an error that "allowImportingTsExtensions" is unknown for TS4.9.
2. Just runs without an error as no TypeScript file exists in the foo directory.

Test code to reproduce

1. Clone https://github.com/sapphi-red-repros/cypress-fails-to-start-allow-ts-extension-ts-4.9
2. Run npm i
3. Run cd foo && npm i
4. Run npm run cypress:run
5. Cypress outputs the message described above and hangs forever

Cypress Version

13.5.1, 13.6.0, 13.8.1, 13.15.1

Node version

v20.9.0, v20.18.0

Operating System

Windows 11 Pro 22H2 22621.2715

Debug Logs

No response

Other

I guess it's related to #28385.

[cypress-app-bot]

This issue has not had any activity in 180 days. Cypress evolves quickly and the reported behavior should be tested on the latest version of Cypress to verify the behavior is still occurring. It will be closed in 14 days if no updates are provided.

[sapphi-red]

This still happens with Cypress 3.15.1.

[achenieux-eyein]

Still happening with 13.16.1

[WDEP-good]

Still happening with 13.17.0

[Radiergummi]

So I figured this out, in a way; if the tsconfig.json is in any way invalid or missing, Cypress will show this behaviour and hang indefinitely. You can verify this by adding "extends": "./missing-file.json" to your tsconfig.json, for example.

I'm really at a loss why Cypress a) would depend on TypeScript in this way, and b) not show a proper error if anything goes wrong at that stage!

[AtofStryker]

this issue will be resolved with #31520 which will be delivered with Cypress 15

Cypress 14.3.1

Cypress 15 prerelease

[AtofStryker]

going to close this issue as it will be resolved with Cypress 15, which is targeted for early July 2025.

[cypress-bot]

Released in 15.0.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v15.0.0, please open a new issue.