Server crash after issuing a task and then leaving the server

[knownout]

Describe the bug
Gave a pawn a task to clear the area and build some houses, and then left the server for 15-20 minutes, after which the server crashed

To Reproduce
Steps or conditions to reproduce the behavior:

1. Give the pawn any task (in my case - clean terrain and build some houses)
2. Left the server for some time (15-20 mins)
3. Server crash

Crash report

java.lang.NullPointerException: Cannot invoke "net.minecraft.class_3222.method_51469()" because "player" is null
        at org.minefortress.tasks.ServerTaskManager.tick(ServerTaskManager.java:70) ~[minefortress-1.11.1-beta.jar:?]
        at org.minefortress.fortress.ServerFortressManager.tick(ServerFortressManager.java:167) ~[minefortress-1.11.1-beta.jar:?]
        at org.minefortress.fortress.server.FortressModServerManager.tick(FortressModServerManager.java:68) ~[minefortress-1.11.1-beta.jar:?]
        at org.minefortress.registries.FortressServerEvents.lambda$register$7(FortressServerEvents.java:94) ~[minefortress-1.11.1-beta.jar:?]
        at net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents.lambda$static$2(ServerTickEvents.java:43) ~[fabric-lifecycle-events-v1-2.2.2+c8b10480a0-cce012c5defdfdc0.jar:?]
        at net.minecraft.server.MinecraftServer.handler$zef000$fabric-lifecycle-events-v1$onEndTick(MinecraftServer.java:2371) ~[server-intermediary.jar:?]
        at net.minecraft.server.MinecraftServer.method_3748(MinecraftServer.java:843) ~[server-intermediary.jar:?]
        at net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:667) ~[server-intermediary.jar:?]
        at net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:263) ~[server-intermediary.jar:?]
        at java.lang.Thread.run(Thread.java:833) ~[?:?]

Environment info:

• OS: Ubuntu 22
• Minecraft version: 1.20.2
• Mod Version 1.11.1-beta

Any other mods that you use
Only server-side mods (terrain generation)