🐛 Fix Web3Auth callback

Author: GabrielePicco

Runtime/Plugins/Web3AuthSDK/Web3Auth.cs

@@ -302,6 +302,7 @@ public void setResultUrl(Uri uri)
         if (hash == null)
             throw new UserCancelledException();
 #endif
+        if(hash.Length == 0) return;
         hash = hash.Remove(0, 1);
         Dictionary<string, string> queryParameters = Utils.ParseQuery(uri.Query);