fix puterjs throwing errors after consuming message events not meant for it (#1612)

src/puter-js/src/modules/UI.js

@@ -275,6 +275,7 @@ class UI extends EventListener {
         // Bind the message event listener to the window
         let lastDraggedOverElement = null;
         (globalThis.document) && window.addEventListener('message', async (e) => {
+            if (!e.data) return;
             // `error`
             if(e.data.error){
                 throw e.data.error;

src/puter-js/src/services/XDIncoming.js

@@ -20,7 +20,7 @@ export class XDIncomingService extends putility.concepts.Service {
             }
 
             const data = event.data;
-
+            if ( ! data ) return;
             const tag = data.$;
             if ( ! tag ) return;
             if ( ! this.tagged_listeners_[tag] ) return;