Fix publicUrl function

src/helpers/publicUrl.ts

@@ -4,8 +4,30 @@
  * @param path - path to prepend prefix to
  */
 export function publicUrl(path: string): string {
+  // The baseUrl must be ending with the slash. The reason is if the baseUrl will
+  // equal to "/my-base", then passing the path equal to "tonconnect-manifest.json" will not
+  // give us the expected result, it will actually be "/tonconnect-manifest.json", but the expected
+  // one is "/my-base/tonconnect-manifest.json". This is due to the URL constructor.
+  let baseUrl = import.meta.env.BASE_URL;
+  if (!baseUrl.endsWith('/')) {
+    baseUrl += '/';
+  }
+
+  let isBaseAbsolute = false;
+  try {
+    new URL(baseUrl);
+    isBaseAbsolute = true;
+  } catch { /* empty */
+  }
+
   return new URL(
+    // The path is not allowed to be starting with the slash as long as it will break the
+    // base URL. For instance, having the "/my-base/" base URL and path
+    // equal to "/tonconnect-manifest.json", we will not get the expected result like
+    // "/my-base/tonconnect-manifest.json", but "/tonconnect-manifest.json".
     path.replace(/^\/+/, ''),
-    window.location.origin + import.meta.env.BASE_URL
+    isBaseAbsolute
+      ? baseUrl
+      : window.location.origin + baseUrl,
   ).toString();
 }