Use string type check before passing into in_default_dir()

Author: westonruter

src/wp-includes/class-wp-scripts.php

@@ -374,7 +374,8 @@ public function do_item( $handle, $group = false ) {
 			$filtered_src = apply_filters( 'script_loader_src', $src, $handle );
 
 			if (
-				$this->in_default_dir( $filtered_src )
+				is_string( $filtered_src )
+				&& $this->in_default_dir( $filtered_src )
 				&& ( $before_script || $after_script || $translations_stop_concat || $this->is_delayed_strategy( $strategy ) )
 			) {
 				$this->do_concat = false;

src/wp-includes/class-wp-styles.php

@@ -183,7 +183,7 @@ public function do_item( $handle, $group = false ) {
 		}
 
 		if ( $this->do_concat ) {
-			if ( $src && $this->in_default_dir( $src ) && ! isset( $obj->extra['alt'] ) ) {
+			if ( is_string( $src ) && $this->in_default_dir( $src ) && ! isset( $obj->extra['alt'] ) ) {
 				$this->concat         .= "$handle,";
 				$this->concat_version .= "$handle$ver";