color_scheme fix.

Author: kprovance

redux-core/inc/extensions/color_scheme/color_scheme/inc/class-redux-color-scheme-functions.php

@@ -26,16 +26,16 @@ class Redux_Color_Scheme_Functions {
 		/**
 		 * Field ID
 		 *
-		 * @var string
+		 * @var string|null
 		 */
-		public static string $field_id;
+		public static ?string $field_id;
 
 		/**
 		 * Field class.
 		 *
-		 * @var string
+		 * @var string|null
 		 */
-		public static string $field_class;
+		public static ?string $field_class;
 
 		/**
 		 * Field array.
@@ -47,23 +47,23 @@ class Redux_Color_Scheme_Functions {
 		/**
 		 * WP Upload directory.
 		 *
-		 * @var string
+		 * @var string|null
 		 */
-		public static string $upload_dir;
+		public static ?string $upload_dir = '';
 
 		/**
 		 * WP Upload URI
 		 *
-		 * @var string
+		 * @var string|null
 		 */
-		public static string $upload_url;
+		public static ?string $upload_url = '';
 
 		/**
 		 * Select fields.
 		 *
-		 * @var array
+		 * @var array|null
 		 */
-		public static array $select;
+		public static ?array $select;
 
 		/**
 		 * Class init.