[15:12:36 WARN]: [Slimefun] Task #14 for Slimefun vDEV - 495 (git e57e4c82) generated an exception
java.lang.NullPointerException: null
        at me.mrCookieSlime.Slimefun.cscorelib2.chat.json.CustomBookInterface.lambda$open$0(CustomBookInterface.java:129) ~[?:?]
        at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftTask.run(CraftTask.java:84) ~[patched_1.13.2.jar:git-Paper-655]
        at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:449) ~[patched_1.13.2.jar:git-Paper-655]
        at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:1010) ~[patched_1.13.2.jar:git-Paper-655]
        at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:439) ~[patched_1.13.2.jar:git-Paper-655]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:940) ~[patched_1.13.2.jar:git-Paper-655]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:837) ~[patched_1.13.2.jar:git-Paper-655]
        at java.lang.Thread.run(Thread.java:834) [?:?]