Problem with header in customization mode

Hello world,

I have a problem with Alexandria Theme when I am in customization mode.
Header do not appear and I have this message :

( ! ) Warning: Creating default object from empty value in C:\wamp64\www\my-site\iRM\wp-content\themes\alexandria\inc\customizer.php on line 47
Call Stack
# Time Memory Function Location
1 0.0021 241360 {main}( ) …\index.php:0
2 0.0038 244464 require( ‘C:\wamp64\www\my-site\iRM\wp-blog-header.php’ ) …\index.php:17
3 0.0055 264496 require_once( ‘C:\wamp64\www\my-site\iRM\wp-load.php’ ) …\wp-blog-header.php:12
4 0.0071 275448 require_once( ‘C:\wamp64\www\my-site\iRM\wp-config.php’ ) …\wp-load.php:37
5 0.0103 400952 require_once( ‘C:\wamp64\www\my-site\iRM\wp-settings.php’ ) …\wp-config.php:89
6 1.4390 25332528 do_action( ) …\wp-settings.php:413
7 1.4396 25337624 call_user_func_array:{C:\wamp64\www\my-site\iRM\wp-includes\plugin.php:525} ( ) …\plugin.php:525
8 1.4396 25337720 WP_Customize_Manager->wp_loaded( ) …\plugin.php:525
9 1.4396 25337808 do_action( ) …\class-wp-customize-manager.php:583
10 1.5091 25651728 call_user_func_array:{C:\wamp64\www\my-site\iRM\wp-includes\plugin.php:525} ( ) …\plugin.php:525
11 1.5091 25658616 alexandria_customize_register( ) …\plugin.php:525

If I put line 47 of customizer.php between “/* … */”, header works well in customization mode.

Need your help. Thank you in advance !

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My details

– WordPress : 4.4.2
– PHP/MySQL : 5.6.16