Collectible Card Game Headquarters

My brother and I played a few games against each other in which Hellspark Elemental was used. My brother was the client and I was the server. When his Hellspark Elemental was to be exiled at the end of the turn after using its "Unearth" ability, both players had "Waiting for opponent" simultaneously indefinitely, which caused us to be unable to continue. This happened repeatedly, ruining our games each time. Please fix the possibility of such a state.