Bug Summary: When sideboarding for a deck with a companion enabled, sideboarding in cards that are incompatible with the companion and clicking Submit without first removing the companion breaks sideboarding. By "breaks" I mean it reloads the UI with an unsideboarded deck, none of the sideboard cards are visible, and you can't interact with the deck or anything else until the timer reaches 0, at which point you'll be loaded into game 2 with the original un-sideboarded deck.

Platform: PC

Steps to Reproduce:
- Create a deck with a Companion (ie. Jegantha)
- Load into a traditional game and finish game 1 to get to sideboarding
- Sideboard in a card that would normally be illegal with the companion (ie. The Meathook Massacre with Jegantha)
- Click "Done" without first removing the companion

Suggestion: Display an error message saying that the player's deck is illegal and / or to remove their companion

Images:

"BeforeSubmitting.png" shows the normal sideboard. I've just added a single copy of The Meathook Massacre for game 2, which you can see is greyed out.

I then click "Done". There is a fade to black and a fade back into the sideboarding screen.

"AfterSubmitting.png" is what the new screen looks like. No sideboard cards are shown, and nothing happens when you click anything in the deck, or the "Done" button. You have to wait on this screen until the timer expires, after which the next game will start without any of the sideboard changes.