Getting errors after creation of functions.php

[janoist1]

I'm getting the following errors after creating even an empty functions.php:

Fatal error: Uncaught Error: Call to undefined function is_blog_installed() in /app/public.built/wp-includes/load.php:606 Stack trace: #0 /app/public.built/wp-settings.php(161): wp_not_installed() #1 /app/public.built/wp-config.php(255): require_once('/app/public.bui...') #2 /app/public.built/wp-load.php(37): require_once('/app/public.bui...') #3 /app/public.built/wp-blog-header.php(13): require_once('/app/public.bui...') #4 /app/public.built/index.php(17): require('/app/public.bui...') #5 {main} thrown in /app/public.built/wp-includes/load.php on line 606

Fatal error: Uncaught Error: Call to undefined function get_option() in /app/public.built/wp-includes/l10n.php:69 Stack trace: #0 /app/public.built/wp-includes/l10n.php(136): get_locale() #1 /app/public.built/wp-includes/l10n.php(756): determine_locale() #2 /app/public.built/wp-includes/class-wp-fatal-error-handler.php(41): load_default_textdomain() #3 [internal function]: WP_Fatal_Error_Handler->handle() #4 {main} thrown in /app/public.built/wp-includes/l10n.php on line 69