Console error log, when opening FakeMobs shop

#ChestCommands fires this WARNING, when opening a FakeMobs shop through a villager:

[21:45:25] [Server thread/WARN]: [ChestCommands] Task #45 for ChestCommands v3.1.2 generated an exception
java.lang.ClassCastException: com.sun.proxy.$Proxy58 cannot be cast to net.minecraft.server.v1_8_R3.EntityVillager
    at net.minecraft.server.v1_8_R3.InventoryMerchant.getOwner(InventoryMerchant.java:43) ~[minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at org.bukkit.craftbukkit.v1_8_R3.inventory.CraftInventory.getHolder(CraftInventory.java:462) ~[minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at com.gmail.filoghost.chestcommands.task.RefreshMenusTask.run(RefreshMenusTask.java:26) ~[ChestCommands.jar:?]
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) ~[minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:722) [minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:653) [minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:556) [minecraft_server.jar:git-Spigot-fdc1440-53fac9f]
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51]