Loop through arguments of a function

wp_enqueue_script states the parameters type respectively as
string - string - array - string - boolean. As you pass an array as the second parameter, the error occurs.

Now, comparing your $array data, you can handle it extracting the array or using array key/value. –

public function loadScripts()
{
    $themeScripts = iarray(
        'custom' => array(
            'src'           => '/includes/js/custom.js',
            'deps'          => 'jquery',
            'ver'           => '4.0',
            'in_footer'     => true     
        ),
        'selecter' => array(
            'src'           => '/includes/js/jquery.fs.selecter.min.js' 
            'deps'          => 'jquery' 
            'ver'           => false,
            'in_footer'     => true
        )
    );

    foreach( $themeScripts as $handle => $args ):

        extract($args);

        wp_enqueue_script( 
            $handle, 
            $src, 
            array($deps), 
            $ver, 
            $in_footer
        );

    endforeach;
}