После этих строк сервер выключается.
14.11 20:17:36 [Server] WARN net.minecraft.server.v1_8_R3.ReportedException: Exception generating new chunk
14.11 20:17:36 [Server] WARN at net.minecraft.server.v1_8_R3.ChunkProviderServer.originalGetChunkAt(ChunkProviderServer.java:150)
14.11 20:17:36 [Server] WARN at net.minecraft.server.v1_8_R3.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:118)
14.11 20:17:36 [Server] WARN at net.minecraft.server.v1_8_R3.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:97)
14.11 20:17:36 [Server] WARN at org.bukkit.craftbukkit.v1_8_R3.CraftServer.createWorld(CraftServer.java:929)
14.11 20:17:36 [Server] WARN at org.bukkit.Bukkit.createWorld(Bukkit.java:464)
14.11 20:17:36 [Server] WARN at org.bukkit.WorldCreator.createWorld(WorldCreator.java:261)
14.11 20:17:36 [Server] WARN at com.onarandombox.MultiverseCore.utils.WorldManager.doLoad(WorldManager.java:421)
14.11 20:17:36 [Server] WARN at com.onarandombox.MultiverseCore.utils.WorldManager.addWorld(WorldManager.java:229)
14.11 20:17:36 [Server] WARN at vc.pvp.skywars.controllers.WorldController.createWorld(WorldController.java:138)
14.11 20:17:37 [Server] WARN at vc.pvp.skywars.controllers.WorldController.(WorldController.java:32)
14.11 20:17:37 [Server] WARN at vc.pvp.skywars.controllers.WorldController.get(WorldController.java:184)
14.11 20:17:37 [Server] WARN at vc.pvp.skywars.SkyWars.onEnable(SkyWars.java:119)
14.11 20:17:37 [Server] WARN at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321)
14.11 20:17:37 [Server] WARN at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340)
14.11 20:17:37 [Server] WARN at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405)
14.11 20:17:37 [Server] WARN at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:357)
14.11 20:17:37 [Server] WARN at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:317)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.MinecraftServer.s(MinecraftServer.java:414)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.MinecraftServer.k(MinecraftServer.java:378)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.MinecraftServer.a(MinecraftServer.java:333)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:263)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:525)
14.11 20:17:37 [Server] WARN at java.lang.Thread.run(Thread.java:748)
14.11 20:17:37 [Server] WARN Caused by: java.lang.OutOfMemoryError: Java heap space
14.11 20:17:37 [Server] WARN at vc.pvp.skywars.utilities.WorldGenerator.generate(WorldGenerator.java:11)
14.11 20:17:37 [Server] WARN at org.bukkit.craftbukkit.v1_8_R3.generator.CustomChunkGenerator.getOrCreateChunk(CustomChunkGenerator.java:129)
14.11 20:17:37 [Server] WARN at net.minecraft.server.v1_8_R3.ChunkProviderServer.originalGetChunkAt(ChunkProviderServer.java:142)
14.11 20:17:37 [Server] WARN…22 more
14.11 20:17:37 [Server] ERROR The world 'island-0' could NOT be loaded because it contains errors!
14.11 20:17:38 [Multicraft] Skipped 2 lines due to rate limit (30/s)
14.11 20:17:38 [Server] ERROR Failed to Create/Load the world 'island-0'
Ошибка создания чанка с помощью кастомного генератора чанков, из-за этого ошибка загрузки мира island-0. Скорее всего в мире ошибка.