Redirection issue with shop isle

From last some month my site is having an issue of redirection. Every single page or link of my site get redirected to the homepage of my site.
for example if i want to open my-account page then it get redirected to the homepage.
all my ads with products link are getting redirected to homepage so i am having total waste of my ads money.

After searching a lot.
I made a look at error log and it was filled with lots of errors. Here are some of them.

for today (29 november)

[29-Nov-2019 06:02:35 UTC] PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘promo_alert’ not found or invalid function name in /home/gharszip/public_html/wp-includes/class-wp-hook.php on line 288
[29-Nov-2019 06:03:14 UTC] postcode was called incorrectly. Customer properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::do_wc_ajax, do_action(‘wc_ajax_update_order_review’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::update_order_review, woocommerce_checkout_payment, wc_get_template, include(‘/plugins/woocommerce/templates/checkout/payment.php’), apply_filters(‘woocommerce_order_button_html’), WP_Hook->apply_filters, postcode_based_order_button_html, WC_Legacy_Customer->__get, wc_doing_it_wrong. This message was added in version 3.0.
[29-Nov-2019 06:03:14 UTC] shipping_postcode was called incorrectly. Customer properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::do_wc_ajax, do_action(‘wc_ajax_update_order_review’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::update_order_review, woocommerce_checkout_payment, wc_get_template, include(‘/plugins/woocommerce/templates/checkout/payment.php’), apply_filters(‘woocommerce_order_button_html’), WP_Hook->apply_filters, postcode_based_order_button_html, WC_Legacy_Customer->__get, wc_doing_it_wrong. This message was added in version 3.0.
[29-Nov-2019 06:03:33 UTC] id was called incorrectly. Order properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::do_wc_ajax, do_action(‘wc_ajax_checkout’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::checkout, WC_Checkout->process_checkout, WC_Checkout->process_order_payment, WC_paytm->process_payment, WC_Abstract_Legacy_Order->__get, wc_doing_it_wrong. This message was added in version 3.0.
[29-Nov-2019 06:03:33 UTC] order_key was called incorrectly. Order properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::do_wc_ajax, do_action(‘wc_ajax_checkout’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::checkout, WC_Checkout->process_checkout, WC_Checkout->process_order_payment, WC_paytm->process_payment, WC_Abstract_Legacy_Order->__get, wc_doing_it_wrong. This message was added in version 3.0.
[29-Nov-2019 06:13:15 UTC] PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘promo_alert’ not found or invalid function name in /home/gharszip/public_html/wp-includes/class-wp-hook.php on line 288

These are some old (30 oct.)

[30-Oct-2019 07:55:39 UTC] PHP Fatal error: Uncaught Error: Call to undefined function is_shop() in /home/gharszip/public_html/wp-content/themes/shop-isle-child/functions.php:50
Stack trace:
#0 /home/gharszip/public_html/wp-includes/class-wp-hook.php(286): shorten_woo_product_title(‘My account’, 7)
#1 /home/gharszip/public_html/wp-includes/plugin.php(208): WP_Hook->apply_filters(‘My account’, Array)
#2 /home/gharszip/public_html/wp-includes/nav-menu.php(825): apply_filters(‘the_title’, ‘My account’, 7)
#3 [internal function]: wp_setup_nav_menu_item(Object(WP_Post))
#4 /home/gharszip/public_html/wp-includes/nav-menu.php(741): array_map(‘wp_setup_nav_me…’, Array)
#5 /home/gharszip/public_html/wp-includes/nav-menu-template.php(140): wp_get_nav_menu_items(Object(WP_Term), Array)
#6 /home/gharszip/public_html/wp-content/themes/shop-isle/inc/structure/header.php(110): wp_nav_menu(Object(stdClass))
#7 /home/gharszip/public_html/wp-includes/class-wp-hook.php(286): shop_isle_primary_navigation(”)
#8 /home/gharszip/public_html/wp-includes/class-wp-hook.php(31 in /home/gharszip/public_html/wp-content/themes/shop-isle-child/functions.php on line 50
[30-Oct-2019 07:55:54 UTC] PHP Fatal error: Uncaught Error: Call to undefined function is_checkout() in /home/gharszip/public_html/wp-content/themes/shop-isle-child/functions.php:27
Stack trace:
#0 /home/gharszip/public_html/wp-includes/class-wp-hook.php(286): my_custom_message(”)
#1 /home/gharszip/public_html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#2 /home/gharszip/public_html/wp-includes/plugin.php(465): WP_Hook->do_action(Array)
#3 /home/gharszip/public_html/wp-includes/template-loader.php(13): do_action(‘template_redire…’)
#4 /home/gharszip/public_html/wp-blog-header.php(19): require_once(‘/home/gharszip/…’)
#5 /home/gharszip/public_html/index.php(17): require(‘/home/gharszip/…’)
#6 {main}
thrown in /home/gharszip/public_html/wp-content/themes/shop-isle-child/functions.php on line 27

Here is the link to my error log file
https://s000.tinyupload.com/index.php?file_id=29188313463445088438

You can download and see the full file.

Let me know if you guys need any other details.

The page I need help with: [log in to see the link]