Prevents warning when closing connection

[marcioAlmada]

Prevents warning when closing connection:

fclose(): supplied resource is not a valid stream resource in ./vendor/amphp/mysql/lib/Processor.php:821

Otherwise aerys application gets unusable with error handlers like:

set_error_handler(function($errno, $errstr, $file, $line) {
    throw new \Exception("{$errstr} in {$file}:{$line}", $errno);
});

[mention-bot]

@marcioAlmada, thanks for your PR! By analyzing the history of the files in this pull request, we identified @bwoebi to be a potential reviewer.

[marcioAlmada]

Funny thing is that this bug occurs within aerys but I can't reproduce in isolation 🤔

[bwoebi]

This is why one does use an error handler like:

set_error_handler(function($errno, $errstr, $file, $line) {
    if (error_reporting()) { // because the @-operator will set error_reporting() === 0
        throw new \Exception("{$errstr} in {$file}:{$line}", $errno);
    }
});

An if (is_resource()) check will only catch one of the potentially warning conditions. Hence it's better to not merge this and just have your error handler handle it properly.

[marcioAlmada]

It concerns me to see untreated warnings in the logs. But I think patching the error handler makes more sense than patching amphp/mysql.

:+1: