Fixed demo mode

Signed-off-by: Trial97 <alexandru.tripon97@gmail.com>

launcher/minecraft/auth/MinecraftAccount.cpp

@@ -269,6 +269,8 @@ void MinecraftAccount::fillSession(AuthSessionPtr session)
     session->player_name = data.profileName();
     // profile ID
     session->uuid = data.profileId();
+    if (session->uuid.isEmpty())
+        session->uuid = uuidFromUsername(session->player_name).toString().remove(QRegularExpression("[{}-]"));
     // 'legacy' or 'mojang', depending on account type
     session->user_type = typeString();
     if (!session->access_token.isEmpty()) {