Stuck in empty king slim arena after re-entering after killing it

[stoic mango]

I finished the king slime boss, then accidentally clicked on the map again and it teleported me to the boss room. But there is seemingly no way out. recall potion just sets me back to the spawn of the boss room and there is no red portal that I had before

[devout furnace]

Every single subworld has the return option, just like Ravencrest. This is covered in the tutorial

Just simply hit the Return button to go to the overworld. This is not a bug but rather intended behavior of our subworld persistence system.