TickProfiling Error

2013-06-19 21:47:01 [SEVERE] [TickProfiler] Failed to save periodic profiling data to ./world/computer/252/profile.txt
java.lang.IllegalArgumentException: Key 'qk['Zombie Pigman'/22177, l='world', x=60,06, y=58,00, z=-170,44]' not present in map
        at com.google.common.base.Preconditions.checkArgument(Preconditions.java:119)
        at com.google.common.base.Functions$FunctionForMapNoDefault.apply(Functions.java:114)
        at com.google.common.collect.ByFunctionOrdering.compare(ByFunctionOrdering.java:46)
        at java.util.TimSort.binarySort(TimSort.java:265)
        at java.util.TimSort.sort(TimSort.java:208)
        at java.util.TimSort.sort(TimSort.java:173)
        at java.util.Arrays.sort(Arrays.java:659)
        at java.util.Collections.sort(Collections.java:217)
        at com.google.common.collect.Ordering.sortedCopy(Ordering.java:519)
        at com.google.common.collect.Ordering.immutableSortedCopy(Ordering.java:540)
        at me.nallar.tickprofiler.minecraft.profiling.EntityTickProfiler.sortedKeys(EntityTickProfiler.java:232)
        at me.nallar.tickprofiler.minecraft.profiling.EntityTickProfiler.writeData(EntityTickProfiler.java:261)
        at me.nallar.tickprofiler.minecraft.profiling.EntityTickProfiler.writeStringData(EntityTickProfiler.java:244)
        at me.nallar.tickprofiler.minecraft.TickProfiler$ProfilingScheduledTickHandler$1.run(TickProfiler.java:190)
        at me.nallar.tickprofiler.minecraft.profiling.EntityTickProfiler$1.run(EntityTickProfiler.java:87)
        at java.lang.Thread.run(Thread.java:722)