fix static analysis

Author: dpanta94

src/Assets/Asset.php

@@ -1825,7 +1825,8 @@ public function do_register() {
 	 */
 	public function set_as_unenqueued() {
 		$this->is_enqueued = false;
-		return $this->dequeue_asset();
+		$this->dequeue_asset();
+		return $this;
 	}
 
 	/**
@@ -1838,7 +1839,8 @@ public function set_as_unenqueued() {
 	 */
 	public function set_as_unregistered() {
 		$this->is_registered = false;
-		return $this->deregister_asset();
+		$this->deregister_asset();
+		return $this;
 	}
 
 	/**