Exception when running multiple sync tests with mixed collections

[papafe]

I'm getting a crash with the following error message: libc++abi: terminating due to uncaught exception of type realm::KeyNotFound: No object with key '0' in 'class_MixedClass' when running multiple tests in the js repo about synced collections in mixed.

The tests are here: https://github.com/realm/realm-js/blob/6c51611bf1a677e2c352ea5404dda8c5094824c2/integration-tests/tests/src/tests/sync/mixed.ts#L408. Using this commit is the best way to reproduce the error, as running the tests with npm test --workspace @realm/node-tests will just run the tests in this suite.

Some additional notes:

• The crash happens only when adding objects to the values that are added to the collections in mixed.
• Each test run on its own succeeds, the crash happens only when running multiple tests together.
• The crash does not happen always, just about 60% of the times.

Relative stack strace:

Origin of the crash:

[sync-by-unito]

➤ PM Bot commented:

Jira ticket: RCORE-2108

[papafe]

Verified that the connected PR solves the issue