Exception thrown, when user logs in during checkout.

#8 🐛 Exception thrown, when user logs in during checkout. Fixed solves the main problem but i experience a new one when i put something in the cart as anonymous and log in in the first step of the checkout:
Type: commerce_order
Message: RuntimeException: Failed to start the session because headers have already been sent by ".../vendor/symfony/http-foundation/Response.php" at line 384. in Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage->start() (line 152 of .../vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php).

is there anybody else who experiences this?

core: 9.5.2
commerce core: 8.x-2.33
commerce_combine_carts: 8.x-1.0-rc2
used patch: #8 🐛 Exception thrown, when user logs in during checkout. Fixed

As the patch #8 is not applicable anymore, I created a MR !11 with the same fix.