try fix syntax error

app.py

@@ -17,12 +17,14 @@ def process_message(message):
     state.context = message
     return message
 
-js = """(() => {
+js = """
+(() => {
     const messageHandler = (event) => {
         alert('test');
     };
     window.addEventListener('message', messageHandler);
-})();"""
+})();
+"""
 
 with gr.Blocks(js=js) as demo:
     with gr.Row():