我在 AnyLogic 中遇到空指针异常

如何解决我在 AnyLogic 中遇到空指针异常

我想知道为什么我在 annylogic 中收到空指针异常。我正在关注本教程：https://www.youtube.com/watch?v=oHMsmTfkhRg。并且，在尝试在 26:00 之后运行模型之后。我收到此错误：

Error during model startup:
NullPointerException
java.lang.NullPointerException
    at hybrid___enviornmental_contamination.Person.executeActionOf(Person.java:251)
    at com.anylogic.engine.Statechart.start(UnkNown Source)
    at hybrid___enviornmental_contamination.Person.doStart(Person.java:615)
    at com.anylogic.engine.Agent.startAsEmbedded(UnkNown Source)
    at hybrid___enviornmental_contamination.Main.doStart(Main.java:1060)
    at com.anylogic.engine.Agent.startAsEmbedded(UnkNown Source)
    at com.anylogic.engine.Agent.start(UnkNown Source)
    at com.anylogic.engine.Engine.start(UnkNown Source)
    at com.anylogic.engine.ExperimentSimulation.m(UnkNown Source)
    at com.anylogic.engine.ExperimentSimulation.run(UnkNown Source)
    at com.anylogic.engine.ExperimentSimulation.k(UnkNown Source)
    at com.anylogic.engine.internal.c$c.run(UnkNown Source)

有人可以帮我吗？？请...