fix: await Sentry. flush() on Vercel

[natterstefan]

Debugging

With Try Catch: ✅

• https://next-with-sentry-77vctt7to-natterstefan.vercel.app/api/test4 (7a2ca0a)

Log on Vercel

Without Try Catch: ❌

• https://next-with-sentry-8igh5sq0h-natterstefan.vercel.app/api/test4 (862be23)

Log on Vercel

Vercel Logs

The false log on Vercel comes from the await Sentry.flush(2000)

Promise.reject vs. Promise.resolve

If you provide a timeout and the queue takes longer to drain the promise returns false.

// src: https://github.com/getsentry/sentry-javascript/blob/a732ae830b613f0227330b93038695ad678ed591/packages/node/src/sdk.ts#L153

/**
 * A promise that resolves when all current events have been sent.
 * If you provide a timeout and the queue takes longer to drain the promise returns false.
 *
 * @param timeout Maximum time in ms the client should wait.
 */
export async function flush(timeout?: number): Promise<boolean> {
  const client = getCurrentHub().getClient<NodeClient>();
  if (client) {
    return client.flush(timeout);
  }
  return Promise.reject(false);
}

They do not resolve but reject the promise. The comment was misleading...

This try/catch solution was mentioned here as well.

Also, the with-sentry example does not indicate that you should try/catch await Sentry.flush as well (https://github.com/vercel/next.js/blob/9ab916ac99eb200a478c8d5ffe94b6ec9c0a315b/examples/with-sentry/pages/api/test4.js#L12).

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[natterstefan]

Update 2021-06-30

I created a PR in the next.js repo with the try/catch solution: vercel/next.js#26767. While I was creating it I found this comment getsentry/sentry-javascript#3643 (comment) in an issue describing my problem with Sentry.flush. Interestingly withSentry handles it silently (mentioned here).

The maintainers of @sentry/nextjs catch it as well: getsentry/sentry-javascript@6c1b4bd#diff-1d2c03eeaa78dd1674379a1628e39b2026cb775d32aea72a366702db9aba1325 😅.

And let's see what happens here getsentry/sentry-javascript#3746.

[natterstefan]

I can confirm, that "@sentry/nextjs": "6.13.2" (as suggested here) resolves the issue (f768137, also with next@11 918f374)

Demo URL: https://next-with-sentry-31rtz63z3-natterstefan.vercel.app/api/test4