Failed IOs hang the runner on JS

[kubukoz]

package demo

import cats.effect.IO
import weaver._

object DemoTest extends SimpleIOSuite {

  test("this should fail rather than hang") {
    IO.unit *> IO.raiseError(new Throwable("woop woop")).as(success)
  }
}

This appears to hang on JS on both Scala 2.13.12 and 3.3.1.

Other versions involved:

• sbt: 1.9.8
• scala.js: 1.15.0
• weaver: 0.8.3

I will confirm whether this is a Weaver problem specifically or a regression in the other releases.

Full repro, with crossproject for comparison against the JVM: https://github.com/kubukoz/demos/tree/repro-js-fail-hang

Update: this seems to have started between 0.7.15 and 0.8.0. Diff: v0.6.15...v0.8.0

Update 2: bisected down to #563.