"Fatal" flag on closed-state connection error is lost for PromiseConnection

[sergburn]

Upon fatal error any connection is set to "closed" state so that its addCommand would throw specific error, which has no code assigned, but has fatal=true flag (see _addCommandClosedState()).

When client attempts to call query() on such connection, this error is forwarded to command callback: cmd.onResult(err). However, if this is PromiseConnection, the error is passed via makeDoneCb() wrapper, which creates another error object to reject the promise but does not copy fatal property. As a result, client receives "closed-state" error without fatal flag. For non-Promise connections it works correctly.

It can be reproduced with something like this:

  const mysql = require('mysql2/promise');

  it('fatal add promise', async () => {
    await startMockServer();

    const conn = await mysql.createConnection(connectionOptions);

    await shutMockServer();

    try {
      await conn.query('SELECT 1');
      expect.fail();
    } catch (err) {
      expect(err).to.be.instanceOf(Error); // OK
      expect(err.message).to.equal("Can't add new command when connection is in closed state"); // OK
      expect(err.fatal).to.equal(true); // ERROR because `fatal` is undefined
    }
  });