wordpress Call to a member function add_section() on a non-object in functions.php line 5
You're missing the $wp_customize argument. And, if I'm not mistaken, it might be an idea to use a different name for add_setting and add_control. See the code below.
function sandor_hero_cap($wp_customize) { $wp_customize->add_section('sandor_subhead_title', array( 'title' => __('Sub-Header', 'sandor'),)); $wp_customize->add_setting('sandor_playground', array( 'default' => 'A Virtual PLAYGROUND', 'capability' => 'edit_theme_options', 'sanitize_callback' => 'sanitize_text_field'));$wp_customize->add_control('sandor_playground', array( 'label' => __('Sub-Header Title', 'sandor'), 'section' => 'sandor_subhead_section', 'priority' => 5, 'settings' => 'sandor_subhead_title'));}add_action( 'customize_register', 'sandor_hero_cap' );