Sorry to hear it had an error opening your pack Backspace4353. Yeah if it errors your cards won't be lost they will end up on your inactive roster which you can get to by going to the Roster management>Manage inactive cards.
But yeah I understand the disappointment for not getting to see the card opening pack animation. As a player myself its fun to hear the rip and pulling out the cards. Even if I mostly have terribly bad pack RNG and get mostly standard cards.