Target from self.onmessage: [object DedicatedWorkerGlobalScope]
Target from message event listener: [object DedicatedWorkerGlobalScope]
Arguments from self.onerror: [
  "Uncaught Error: Some error message",
  "[WILDCARD]/worker_event_handlers.js",
  9,
  9,
  Error: Some error message
    at [WILDCARD]
]
Is event canceled?: true