Crash upon defeating floor bosses

[AvangionQ]

After beating a floor boss, the game instantly crashes to desktop ... when I go back into the game, the rewards don't include the next set of three spire challenges.

Exception: java.util.ConcurrentModificationException 01:55:55.250 ERROR core.CardCrawlGame> Exception caught java.util.ConcurrentModificationException: null at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) ~[?:1.8.0_144] at java.util.ArrayList$Itr.remove(ArrayList.java:865) ~[?:1.8.0_144] at com.megacrit.cardcrawl.dungeons.AbstractDungeon.update(AbstractDungeon.java:2648) ~[?:?] at com.megacrit.cardcrawl.core.CardCrawlGame.update(CardCrawlGame.java:878) ~[?:?] at com.megacrit.cardcrawl.core.CardCrawlGame.render(CardCrawlGame.java:429) [?:?] at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225) [?:?] at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126) [desktop-1.0.jar:?] Controllers: removed manager for application, 0 managers active Game closed.