fix(example): resolve race between async Maps callback and deferred ESM module

Google Maps loaded with async+callback could fire before the type=module script assigned window.initApp, leaving the map blank. Stub initApp as a promise resolver synchronously, await it inside the module.

Author: cyphercodes

example/index.html

@@ -396,6 +396,13 @@ <h2>Presets</h2>
       </div>
     </footer>
 
+    <!-- Bridge: Maps' async callback resolves a promise the module awaits. -->
+    <script>
+      window.__mapsReady = new Promise((resolve) => {
+        window.initApp = resolve;
+      });
+    </script>
+
     <!-- Google Maps JS API. Replace YOUR_API_KEY. -->
     <script
       async
@@ -414,7 +421,8 @@ <h2>Presets</h2>
         el.className = 'status' + (cls ? ' ' + cls : '');
       }
 
-      window.initApp = function () {
+      await window.__mapsReady;
+      (function init() {
         const latView = $('latView');
         const lngView = $('lngView');
 
@@ -493,7 +501,7 @@ <h2>Presets</h2>
           lp.setLocation(lat, lng);
           updateView({ lat, lng });
         });
-      };
+      })();
     </script>
   </body>
 </html>