Sidebar not showing up

Hello,

I was updating my website and decided to start fresh and get a new theme. But the sidebar is not showing up, i switched to another theme but the same problem and error code showed up:

Warning: Illegal string offset 'sidebar' in /customers/e/b/9/feels.be/httpd.www/wp-content/themes/holistic/sidebar.php on line 26

Warning: Illegal string offset 'sidebar_position' in /customers/e/b/9/feels.be/httpd.www/wp-content/themes/holistic/sidebar.php on line 27

Can someone help me or explain me this?

Hi!

All these notices are just warnings which could be hidden by disabling the WP_DEBUG option.
Please, use the instruction on how to hide php warnings: https://codex.wordpress.org/WP_DEBUG