SDK fails in ESM mode in combination with date-fns

[Xhale1]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/node

SDK Version

8.2.1

Framework Version

Nodejs 20.13.1

Link to Sentry event

https://mycopilot.sentry.io/issues/5344731586/?project=6067364&query=is%3Aunresolved&referrer=issue-stream&statsPeriod=24h&stream_index=0

SDK Setup

Sentry.init({
  dsn: "[REDACTED]",
});

Steps to Reproduce

1. Upgrade from v7 to v8 following the migration docs
2. Follow Sentry docs for ESM
3. Add --import ./dist/instrument.js to the node command

Expected Result

Application starts up.

Actual Result

Application crashes with an error which seems to involve duplicate exports with ESM. An example of my particular error:

SyntaxError: Identifier '$longFormatters' has already been declared
    at ModuleLoader.moduleStrategy (node:internal/modules/esm/translators:169:18)
    at callTranslator (node:internal/modules/esm/loader:272:14)
    at ModuleLoader.moduleProvider (node:internal/modules/esm/loader:278:30)

Upon investigating, I found my error to be related to the date-fns package and this issue. Reverting date-fns to a version without a duplicate export results in another similar error (I suspect related to the openai package duplicate export though haven't confirmed).

This issue does not occur when using the --import flag to load a file without sentry code in it, and it doesn't surface elsewhere. This error may be due to other projects misusing ESM, though I hope since the issue only surfaces with Sentry instrumentation that it may be solvable here.

[timfish]

Interesting, I wonder why the loader triggers this 🤔

Do you just have only the Sentry.init in ./dist/instrument.js and instrument.js fully ESM?

If you add this before Sentry.init, do you still get the error?

globalThis._sentryEsmLoaderHookRegistered = true

[dankochetov]

If you add this before Sentry.init, do you still get the error?

I'm having the same issue (just with a different import name) and adding this line fixes it for me.

[timfish]

adding this line fixes it for me.

Be aware that globalThis._sentryEsmLoaderHookRegistered = true disables OpenTelemetry auto-instrumentation so you will lose those features.