unhandled exceptions kill server

[jaked]

e.g. this code in a cell

import * as Domain from "node:domain";

const d = Domain.create();
const p = d.run(async () => {
  throw new Error("test");
});

throws a server-killing exception, I think because the promise isn't awaited in the code path that handles exceptions. I think there's a top-level exception handler we need to set, and also we need to clean up the cell execution state.