Problem with type unions on errors

import { Effect, Random } from "effect";

class ErrorOne {
  _tag = "CustomerExistsError";
}

class ErrorTwo {
  _tag = "DatabaseError";
}

const program = Effect.gen(function* () {
  // Generate two random numbers between 0 and 1
  const n1 = yield* Random.next;
  const n2 = yield* Random.next;

  // Simulate an HTTP error
  if (n1 < 0.5) {
    yield* Effect.fail(new ErrorOne());
  }
  // Simulate a validation error
  if (n2 < 0.5) {
    yield* Effect.fail(new ErrorTwo());
  }

  return "some result";
});