test is flaky

[Simon-Laux]

yarn test sometimes work but sometimes it exits with an error code.
I did not find the source of this issue.

[Simon-Laux]

The bug is inside of __test__/index.spec.ts, the other test (__test__/low_level.spec.ts) works.

I found out that if we run ava with --no-worker-threads it works every time locally.
So this is somewhere in the combination of ava's worker threads and the JsonRpcClient.
Maybe something about the event emitter?