Fix calling then on connecting that can be null

[choval]

After some idle time, the fist call gets:

Fatal error: Uncaught Error: Call to a member function then() on null in .../vendor/react/mysql/src/Io/LazyConnection.php:94

Due to connecting attribute being null, changed to connecting() method.

[clue]

@choval Thanks for spotting and reporting!

Unfortunately, the PR does not contain any documentation or tests, so it's a bit unclear what you're trying to achieve from the snippet you've posted.

May I ask you provide a simple gist of what you're trying to achieve, i.e. how can this be reproduced and how can we be sure this issue is actually resolved and we do not introduce any regressions in the future? Thanks!

[choval]

Having a hard time reproducing this.

What basically happens is the connection closes on the database side, the connection is nullified before the idleTimer is cancelled.

mysql/src/Io/LazyConnection.php

Lines 62 to 69 in c420ca0

	$connection->on('close', function () {
	$this->connecting = null;
	if ($this->idleTimer !== null) {
	$this->loop->cancelTimer($this->idleTimer);
	$this->idleTimer = null;
	}
	});

My script somehow managed to run the idleTimer before the cancelTimer, and after connecting = null (yay for async).

So, my proposal would actually trigger a new connection, which is totally wrong, since the whole purpose of the timer is to idle it... not reconnect it. (Made it in a hurry, since it breaks the server with a fatal error)

I'm thinking, maybe check if its null or canceling the timer before nullifying connecting?

nullifying connecting after canceling the timer

if ($this->idleTimer !== null) {
    $this->loop->cancelTimer($this->idleTimer);
    $this->idleTimer = null;
}
$this->connecting = null;

or just checking if its not null before expecting a promise on connecting

function idle()
{
  --$this->pending;

  if ($this->pending < 1 && $this->idlePeriod >= 0) {
    $this->idleTimer = $this->loop->addTimer($this->idlePeriod, function () {
      if($this->connecting !== null) {
        $this->connecting->then(function (ConnectionInterface $connection) {
          $this->disconnecting = $connection;
          $connection->quit()->then(
            function () {
              // successfully disconnected => remove reference
              $this->disconnecting = null;
            },
            function () use ($connection) {
              // soft-close failed => force-close connection
              $connection->close();
              $this->disconnecting = null;
            }
          );
        });
      }
      $this->connecting = null;
      $this->idleTimer = null;
    });
  }
}