Remove extra deprecations in PHP 8.1

In our website we’ve found a few extra deprecation warning generated from Blocksy’s code.

Probably they depend a lot on our customizations and other installed plugins. This is the patch we’ve developed to fix them:

diff --git a/inc/classes/screen-manager.php b/inc/classes/screen-manager.php
index 7197a0909..00c6481a0 100644
--- a/inc/classes/screen-manager.php
+++ b/inc/classes/screen-manager.php
@@ -42,10 +42,10 @@ class Blocksy_Screen_Manager {
 		}
 
 		$result = strpos(
-			$current_template,
+			$current_template ?? '',
 			WC()->plugin_path() . '/templates/'
 		) !== false || strpos(
-			$current_template,
+			$current_template ?? '',
 			get_template_directory()
 		) !== false;
 
diff --git a/inc/components/hero-section.php b/inc/components/hero-section.php
index 8c8c06b93..3e18067b5 100644
--- a/inc/components/hero-section.php
+++ b/inc/components/hero-section.php
@@ -38,7 +38,7 @@ if (! function_exists('blocksy_get_page_title_source')) {
 			return $result;
 		}
 
-		if (strpos($prefix, 'single') !== false || (
+		if (strpos($prefix ?? '', 'single') !== false || (
 			function_exists('is_shop') && is_shop()
 		) && ! is_search()) {
 			$post_options = blocksy_get_post_options();
diff --git a/inc/sidebar.php b/inc/sidebar.php
index 0f4b1d248..20e411c88 100644
--- a/inc/sidebar.php
+++ b/inc/sidebar.php
@@ -182,7 +182,7 @@ if (! function_exists('blocksy_sidebar_position_unfiltered')) {
 		]);
 
 		if (
-			strpos($prefix, '_archive') !== false
+			strpos($prefix ?? '', '_archive') !== false
 			||
 			$prefix === 'search'
 			||
@@ -220,7 +220,7 @@ if (! function_exists('blocksy_sidebar_position_unfiltered')) {
 			&&
 			$prefix !== 'product'
 			&&
-			strpos($prefix, '_single') === false
+			strpos($prefix ?? '', '_single') === false
 			&&
 			(
 				$prefix !== 'courses_archive'