[13:33:10 WARN]: java.lang.NullPointerException: Nodes must be provided.
[13:33:10 WARN]:        at org.yaml.snakeyaml.nodes.NodeTuple.<init>(NodeTuple.java:28)
[13:33:10 WARN]:        at org.yaml.snakeyaml.representer.BaseRepresenter.representMapping(BaseRepresenter.java:163)
[13:33:10 WARN]:        at org.yaml.snakeyaml.representer.SafeRepresenter$RepresentMap.representData(SafeRepresenter.java:304)
[13:33:10 WARN]:        at org.yaml.snakeyaml.representer.BaseRepresenter.representData(BaseRepresenter.java:94)
[13:33:10 WARN]:        at org.yaml.snakeyaml.representer.BaseRepresenter.represent(BaseRepresenter.java:64)
[13:33:10 WARN]:        at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:242)
[13:33:10 WARN]:        at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:206)
[13:33:10 WARN]:        at org.yaml.snakeyaml.Yaml.dump(Yaml.java:181)
[13:33:10 WARN]:        at org.bukkit.configuration.file.YamlConfiguration.saveToString(YamlConfiguration.java:39)
[13:33:10 WARN]:        at org.bukkit.configuration.file.FileConfiguration.save(FileConfiguration.java:68)
[13:33:10 WARN]:        at net.citizensnpcs.api.util.YamlStorage.save(YamlStorage.java:106)
[13:33:10 WARN]:        at net.citizensnpcs.api.npc.SimpleNPCDataStore$1.run(SimpleNPCDataStore.java:68)