Fixed the furnace XP bug

Changelog.txt

@@ -1,3 +1,7 @@
+Version 2.1.54
+    Fixed a bug where the Skill 'Understanding the Art' was preventing vanilla experience orbs from furnaces
+    Fixed 'Understanding the Art' not correctly boosting vanilla XP from furnaces
+
 Version 2.1.53
     Fixed a critical bug where players earned too much XP
 

pom.xml

@@ -2,7 +2,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.gmail.nossr50.mcMMO</groupId>
     <artifactId>mcMMO</artifactId>
-    <version>2.1.53</version>
+    <version>2.1.54</version>
     <name>mcMMO</name>
     <url>https://github.com/mcMMO-Dev/mcMMO</url>
     <scm>

src/main/java/com/gmail/nossr50/listeners/InventoryListener.java

@@ -190,7 +190,8 @@ public class InventoryListener implements Listener {
             return;
         }
 
-        int exp = UserManager.getPlayer(player).getSmeltingManager().vanillaXPBoost(event.getExpToDrop());
+        int xpToDrop = event.getExpToDrop();
+        int exp = UserManager.getPlayer(player).getSmeltingManager().vanillaXPBoost(xpToDrop);
         event.setExpToDrop(exp);
     }
 

src/main/java/com/gmail/nossr50/skills/smelting/SmeltingManager.java

@@ -131,6 +131,6 @@ public class SmeltingManager extends SkillManager {
      * @return the vanilla XP multiplier
      */
     public int getVanillaXpMultiplier() {
-        return RankUtils.getRank(getPlayer(), SubSkillType.SMELTING_UNDERSTANDING_THE_ART);
+        return Math.max(1, RankUtils.getRank(getPlayer(), SubSkillType.SMELTING_UNDERSTANDING_THE_ART));
     }
 }