I use an exception handling service in my plugin that allows me to track errors caused by my plugins. Occasionally I get other errors. This is one such example. Stacktrace below:

ArrayIndexOutOfBoundsException: 189
at it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap.get (Long2ObjectOpenHashMap.java:374)
at net.minecraft.server.v1_10_R1.ChunkProviderServer.getChunkIfLoaded (ChunkProviderServer.java:110)
at net.minecraft.server.v1_10_R1.ChunkProviderServer.getChunkAt (ChunkProviderServer.java:123)
at net.minecraft.server.v1_10_R1.ChunkProviderServer.getChunkAt (ChunkProviderServer.java:119)
at net.minecraft.server.v1_10_R1.ChunkProviderServer.getChunkAt (ChunkProviderServer.java:115)
at org.bukkit.craftbukkit.v1_10_R1.CraftWorld.getChunkAt (CraftWorld.java:129)
at org.bukkit.craftbukkit.v1_10_R1.CraftWorld.getBlockAt (CraftWorld.java:93)
at org.bukkit.craftbukkit.v1_10_R1.CraftWorld.getBlockAt (CraftWorld.java:559)
at org.bukkit.Location.getBlock (Location.java:87)
at me.egg82.tcpp.lib.ninja.egg82.plugin.utils.BlockUtil.getTopWalkableBlock (BlockUtil.java:102)
at me.egg82.tcpp.ticks.LsdTickCommand.getFilledCircle (LsdTickCommand.java:88)
at me.egg82.tcpp.ticks.LsdTickCommand.access$100 (LsdTickCommand.java:25)
at me.egg82.tcpp.ticks.LsdTickCommand$1.run (LsdTickCommand.java:57)
at java.lang.Thread.run ([unknown]:-1)

getTopWalkableBlock as referenced can be found here with the specific line referenced here.