Fatal error: Uncaught Error: Unsupported operand types: string + int
in /usr/www/users/autogab/chiptuning-berlin/wp-content/themes/chiptuningberlin/content-singletuning.php on line 228

Call stack:

1. require()
   wp-includes/template.php:812
2. load_template()
   wp-includes/template.php:745
3. locate_template()
   wp-includes/general-template.php:206
4. get_template_part()
   wp-content/themes/generatepress/inc/theme-functions.php:568
5. generate_do_template_part()
   wp-content/themes/chiptuningberlin/single-chiptuning.php:29
6. include()
   wp-includes/template-loader.php:106
7. require_once()
   wp-blog-header.php:19
8. require()
   index.php:17