theme php error (page is broken!)

hi there thanks for the beautifl theme but

I have trouble about this site. theme have php error. it’s broken page.. can you please fix it?

many time.. not only 1or 2time.. it’s showing broken page

please let me know what can i do

[08-Apr-2024 08:29:44 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in /public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[09-Apr-2024 08:38:27 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in /home/customer/www/thepaddockwa.com/public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[10-Apr-2024 07:48:29 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[11-Apr-2024 09:15:01 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[12-Apr-2024 08:32:03 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[13-Apr-2024 09:01:35 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[14-Apr-2024 08:54:25 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[15-Apr-2024 09:08:21 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in /public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[16-Apr-2024 08:54:40 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in /public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}

thrown in public_html/wp-content/themes/vertice/index.php on line 3
[17-Apr-2024 09:05:04 UTC] PHP Fatal error: Uncaught Error: Call to undefined function get_header() in public_html/wp-content/themes/vertice/index.php:3
Stack trace: 0 {main}