[13:10:17] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.util.ReportedException: Ticking memory connection
    at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:198) ~[NetworkSystem.class:?]
    at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:726) ~[MinecraftServer.class:?]
    at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614) ~[MinecraftServer.class:?]
    at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118) ~[IntegratedServer.class:?]
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485) [MinecraftServer.class:?]
    at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752) [MinecraftServer$2.class:?]
Caused by: java.lang.NullPointerException
    at com.princecat.treasuretrails.common.clue.ClueManager.serialize(ClueManager.java:293) ~[ClueManager.class:?]
    at com.princecat.treasuretrails.common.clue.ClueManager.serialize(ClueManager.java:29) ~[ClueManager.class:?]
    at com.google.gson.TreeTypeAdapter.write(TreeTypeAdapter.java:70) ~[TreeTypeAdapter.class:?]
    at com.google.gson.Gson.toJson(Gson.java:593) ~[Gson.class:?]
    at com.google.gson.Gson.toJson(Gson.java:572) ~[Gson.class:?]
    at com.google.gson.Gson.toJson(Gson.java:527) ~[Gson.class:?]
    at com.princecat.treasuretrails.common.clue.ClueManager.writeToFile(ClueManager.java:314) ~[ClueManager.class:?]
    at com.princecat.treasuretrails.common.clue.ClueManager.<init>(ClueManager.java:69) ~[ClueManager.class:?]
    at com.princecat.treasuretrails.common.item.ItemClueScroll.onItemRightClick(ItemClueScroll.java:36) ~[ItemClueScroll.class:?]
    at net.minecraft.item.ItemStack.useItemRightClick(ItemStack.java:164) ~[ItemStack.class:?]
    at net.minecraft.server.management.ItemInWorldManager.tryUseItem(ItemInWorldManager.java:345) ~[ItemInWorldManager.class:?]
    at net.minecraft.network.NetHandlerPlayServer.processPlayerBlockPlacement(NetHandlerPlayServer.java:576) ~[NetHandlerPlayServer.class:?]
    at net.minecraft.network.play.client.C08PacketPlayerBlockPlacement.processPacket(C08PacketPlayerBlockPlacement.java:74) ~[C08PacketPlayerBlockPlacement.class:?]
    at net.minecraft.network.play.client.C08PacketPlayerBlockPlacement.processPacket(C08PacketPlayerBlockPlacement.java:122) ~[C08PacketPlayerBlockPlacement.class:?]
    at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:241) ~[NetworkManager.class:?]
    at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:182) ~[NetworkSystem.class:?]
    ... 5 more