callable_event.php

<?php

$plugin = $this->plugin($plugin, function($plugin) use($args, $callback) {
    if (!is_callable($plugin)) {
        return $this->call('service:event', [$plugin]); 
    }

    return $plugin;
});

modified_call.php

public function call($config, array $args = [], callable $callback = null)
{
    if (!is_string($config)) {
        return $config instanceof Event ? $this->trigger($config, $args, $callback ?: $this)
            : $this->invoke($config, $args, $callback);
    }

    $config = explode(Args::CALL_SEPARATOR, $config);
    $plugin = array_shift($config);
    $method = array_pop($config);

    $plugin = $this->plugin($plugin, function($plugin) use($args, $callback) {
        if (!is_callable($plugin)) {
            return $this->call('service:event', [$plugin]); 
        }

        return $plugin;
    });

    if ($plugin instanceof Event) {
        return $this->trigger($plugin, $args, $callback ?: $this);
    }

    foreach($config as $name) {
        $plugin = $this->invoke([$plugin, $name], $args, $callback);
    }

    return $this->invoke($method ? [$plugin, $method] : $plugin, $args, $callback);
}