Workflow error rehydrated after crossing the Temporal sandbox boundary.
Preserves name, message, cause, and other enumerable properties from
the serialized form; it is a reconstructed Error, not the original class.
Extra fields are present at runtime but not on the Error type — narrow or
cast in TypeScript when you need them.
Timestamp of the event
UUID v4 stamped per emit. Stable per-emit idempotency key.
Information about the current workflow execution
Payload passed to the onWorkflowError() handler when a workflow run fails.