Version 1.4.1

 * Fix NPE on startup.

pom.xml

@@ -5,7 +5,7 @@
 
     <groupId>nu.nerd</groupId>
     <artifactId>DragonFight</artifactId>
-    <version>1.4.0</version>
+    <version>1.4.1</version>
 
     <description>Custom dragon fight.</description>
     <url>https://github.com/NerdNu/${project.name}</url>

src/main/java/nu/nerd/df/FightState.java

@@ -1478,6 +1478,15 @@ protected void animateNextStage() {
             return;
         }
 
+        // I have observed that sometimes the config has stage-number: 0 and
+        // new-stage-number: 1, and there are no crystals. In that case, getting
+        // the next crystal to remove by _crystals.iterator() fails and there
+        // is an exception. Avoid that.
+        // TODO: work out why we get into this inconsistent state and fix it.
+        if (_crystals.isEmpty()) {
+            return;
+        }
+
         // From here forward, getNewStageNumber() is between 1 and 10.
         // Remove a random crystal. Random order due to hashing UUID.
         EnderCrystal replacedCrystal = _crystals.iterator().next();