Fail fast if world is null when parsing locations.

This commit introduces a null check in the ConfigUtils `parseLocation`
method. If the world of a location string does not exist, the method now
throws an IllegalArgumentException, which allows callers to fail more
gracefully instead of having to resort to null checks.

Additionally, the parsing of exit warps, leaderboards, or linked class
chests is wrapped in try-catch statements that re-throw ConfigErrors
for better error reporting.

Fixes #421

src/main/java/com/garbagemule/MobArena/ArenaMasterImpl.java

@@ -382,8 +382,12 @@ public class ArenaMasterImpl implements ArenaMaster
         loadClassLobbyPermissions(arenaClass, section);
 
         // Check for class chests
-        Location cc = parseLocation(section, "classchest", null);
-        arenaClass.setClassChest(cc);
+        try {
+            Location cc = parseLocation(section, "classchest", null);
+            arenaClass.setClassChest(cc);
+        } catch (IllegalArgumentException e) {
+            throw new ConfigError("Failed to parse classchest location for class " + classname + " because: " + e.getMessage());
+        }
 
         // Finally add the class to the classes map.
         classes.put(lowercase, arenaClass);

src/main/java/com/garbagemule/MobArena/region/ArenaRegion.java

@@ -4,6 +4,7 @@ import static com.garbagemule.MobArena.util.config.ConfigUtils.makeSection;
 import static com.garbagemule.MobArena.util.config.ConfigUtils.parseLocation;
 import static com.garbagemule.MobArena.util.config.ConfigUtils.setLocation;
 
+import com.garbagemule.MobArena.ConfigError;
 import com.garbagemule.MobArena.MAUtils;
 import com.garbagemule.MobArena.MobArena;
 import com.garbagemule.MobArena.framework.Arena;
@@ -81,7 +82,12 @@ public class ArenaRegion
         arenaWarp = parseLocation(coords, "arena", world);
         lobbyWarp = parseLocation(coords, "lobby", world);
         specWarp  = parseLocation(coords, "spectator", world);
-        exitWarp  = parseLocation(coords, "exit", null);
+
+        try {
+            exitWarp = parseLocation(coords, "exit", null);
+        } catch (IllegalArgumentException e) {
+            throw new ConfigError("Failed to parse exit warp for arena " + arena.configName() + " because: " + e.getMessage());
+        }
     }
     
     public void reloadLeaderboards() {
@@ -89,7 +95,7 @@ public class ArenaRegion
         try {
             leaderboard = parseLocation(coords, "leaderboard", null);
         } catch (IllegalArgumentException e) {
-            leaderboard = parseLocation(coords, "leaderboard", world);
+            throw new ConfigError("Failed to parse leaderboard location for arena " + arena.configName() + " because: " + e.getMessage());
         }
         if (leaderboard != null && leaderboard.getWorld() == null) {
             leaderboard.setWorld(world);
@@ -235,7 +241,7 @@ public class ArenaRegion
                 (z + radius >= p1.getBlockZ() && z - radius <= p2.getBlockZ()) &&
                 (y + radius >= p1.getBlockY() && y - radius <= p2.getBlockY()));
     }
-    
+
     // Region expand
     public void expandUp(int amount) {
         int x = p2.getBlockX();

src/main/java/com/garbagemule/MobArena/util/config/ConfigUtils.java

@@ -1,5 +1,6 @@
 package com.garbagemule.MobArena.util.config;
 
+import com.garbagemule.MobArena.ConfigError;
 import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.World;
@@ -119,6 +120,9 @@ public class ConfigUtils
                 throw new IllegalArgumentException("Expected location of type (x,y,z,yaw,pitch,world)");
             }
             world = Bukkit.getWorld(parts[5]);
+            if (world == null) {
+                throw new IllegalArgumentException("World " + parts[5] + " not found");
+            }
         }
         return new Location(world, x, y, z, yaw, pit);
     }