YAML-related 1.12 startup error on 4.0.7

[SXRWahrheit]

[08:53:03] [Craft Scheduler Thread - 0/WARN]: [Autorank] Plugin Autorank v4.0.7 generated an exception while executing task 102
java.lang.NullPointerException: Nodes must be provided.
    at org.yaml.snakeyaml.nodes.NodeTuple.<init>(NodeTuple.java:28) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.BaseRepresenter.representMapping(BaseRepresenter.java:163) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.SafeRepresenter$RepresentMap.representData(SafeRepresenter.java:314) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.bukkit.configuration.file.YamlRepresenter$RepresentConfigurationSection.representData(YamlRepresenter.java:23) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.BaseRepresenter.representData(BaseRepresenter.java:94) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.BaseRepresenter.representMapping(BaseRepresenter.java:156) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.SafeRepresenter$RepresentMap.representData(SafeRepresenter.java:314) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.BaseRepresenter.representData(BaseRepresenter.java:94) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.representer.BaseRepresenter.represent(BaseRepresenter.java:64) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:297) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:261) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.yaml.snakeyaml.Yaml.dump(Yaml.java:236) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.bukkit.configuration.file.YamlConfiguration.saveToString(YamlConfiguration.java:39) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.bukkit.configuration.file.FileConfiguration.save(FileConfiguration.java:68) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at me.armar.plugins.autorank.config.SimpleYamlConfiguration.saveFile(SimpleYamlConfiguration.java:94) ~[?:?]
    at me.armar.plugins.autorank.config.InternalPropertiesConfig.setCachedLeaderboard(InternalPropertiesConfig.java:156) ~[?:?]
    at me.armar.plugins.autorank.leaderboard.LeaderboardHandler.updateLeaderboard(LeaderboardHandler.java:402) ~[?:?]
    at me.armar.plugins.autorank.leaderboard.LeaderboardHandler$4.run(LeaderboardHandler.java:317) ~[?:?]
    at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[server.jar:git-Spigot-ede465d-bb4ae3b]
    at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [server.jar:git-Spigot-ede465d-bb4ae3b]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_111]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_111]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_111]