WordPress Logo Uploader in Theme Customizer

admin.php

/***************CUSTOMIZE THE THEME CUSTOMIZER************/
function refinestl_customize_register( $wp_customize ) {
  // Do stuff with $wp_customize, the WP_Customize_Manager object.
	$wp_customize->add_section( 'logo_section', array(
        'title'    => __( 'Logos', 'textdomain' ),
        'priority' => 101,
    ) );
 
    $wp_customize->add_setting( 'site_logo', array(
        'type' => 'theme_mod',
        'default'           => '',
        'transport'         => 'postMessage', //Shows the new setting in the preview pane instantly (no refresh needed)
        'sanitize_callback' => '',
    ) );
 
    $wp_customize->add_control( new WP_Customize_Media_Control( $wp_customize, 'media_control', array(
    'label' => __( 'Site Logo' ),
    'section' => 'logo_section',
    'settings' => 'site_logo',
) ) );
}
add_action( 'customize_register', 'refinestl_customize_register' );

header.php

$logo_img_id = get_theme_mod('site_logo');
$img_array = wp_get_attachment_image_src ( $logo_img_id, 'medium', false );
$img_src = $img_array[0];