Mini Cart Contents: Fix missing custom background

src/BlockTypes/MiniCart.php

@@ -378,12 +378,12 @@ protected function get_markup( $attributes ) {
 		}
 
 		$template_part_contents = '';
-		if ( function_exists( 'gutenberg_get_block_template' ) ) {
-			$template_part = gutenberg_get_block_template( get_stylesheet() . '//mini-cart', 'wp_template_part' );
-			if ( $template_part && ! empty( $template_part->content ) ) {
-				$template_part_contents = do_blocks( $template_part->content );
-			}
+		$template_part          = BlockTemplateUtils::get_block_template( get_stylesheet() . '//mini-cart', 'wp_template_part' );
+
+		if ( $template_part && ! empty( $template_part->content ) ) {
+			$template_part_contents = do_blocks( $template_part->content );
 		}
+
 		if ( '' === $template_part_contents ) {
 			$template_part_contents = do_blocks(
 				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents

src/Utils/BlockTemplateUtils.php

@@ -352,6 +352,28 @@ public static function supports_block_templates() {
 		return true;
 	}
 
+	/**
+	 * Retrieves a single unified template object using its id.
+	 *
+	 * @param string $id            Template unique identifier (example: theme_slug//template_slug).
+	 * @param string $template_type Optional. Template type: `'wp_template'` or '`wp_template_part'`.
+	 *                             Default `'wp_template'`.
+	 *
+	 * @return WP_Block_Template|null Template.
+	 */
+	public static function get_block_template( $id, $template_type ) {
+		if ( function_exists( 'get_block_template' ) ) {
+			return get_block_template( $id, $template_type );
+		}
+
+		if ( function_exists( 'gutenberg_get_block_template' ) ) {
+			return gutenberg_get_block_template( $id, $template_type );
+		}
+
+		return null;
+
+	}
+
 	/**
 	 * Checks if we can fallback to the `archive-product` template for a given slug
 	 *