Per World Inventories Error

[23:00:57 WARN]: Exception in thread "Craft Scheduler Thread - 20"
[23:00:57 WARN]: org.apache.commons.lang.UnhandledException: Plugin PerWorldInve
ntory v1.7.5 generated an exception while executing task 6312
        at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsy
ncTask.java:56)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
        at me.gnat008.perworldinventory.data.FileSerializer.getFile(FileSerializ
er.java:202)
        at me.gnat008.perworldinventory.data.FileSerializer.saveToDatabase(FileS
erializer.java:64)
        at me.gnat008.perworldinventory.data.DataSerializer$1.run(DataSerializer
.java:59)
        at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftTask.run(CraftTask.jav
a:71)
        at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsy
ncTask.java:53)
        ... 3 more