Scheduler Bug Problem

Code:

2012-10-27 03:00:14 [SEVERE] Exception in thread "pool-1-thread-23"
2012-10-27 03:00:15 [SEVERE] org.apache.commons.lang.UnhandledException: Plugin BuyLand v0.5.B generated an exception while executing task 30
    at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException: Nodes must be provided.
    at org.yaml.snakeyaml.nodes.NodeTuple.<init>(NodeTuple.java:29)
    at org.yaml.snakeyaml.representer.BaseRepresenter.representMapping(BaseRepresenter.java:171)
    at org.yaml.snakeyaml.representer.SafeRepresenter$RepresentMap.representData(SafeRepresenter.java:201)
    at org.yaml.snakeyaml.representer.BaseRepresenter.representData(BaseRepresenter.java:96)
    at org.yaml.snakeyaml.representer.BaseRepresenter.represent(BaseRepresenter.java:66)
    at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:270)
    at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:261)
    at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:233)
    at org.yaml.snakeyaml.Yaml.dump(Yaml.java:209)
    at org.bukkit.configuration.file.YamlConfiguration.saveToString(YamlConfiguration.java:38)
    at org.bukkit.configuration.file.FileConfiguration.save(FileConfiguration.java:54)
    at me.buyland.buyland.main.saveRentConfig(main.java:173)
    at me.buyland.buyland.main$1.run(main.java:306)
    at org.bukkit.craftbukkit.scheduler.CraftTask.run(CraftTask.java:53)
    at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
    ... 3 more

I am trying to figure out why my plugin keeps erroring out. This is my error message. I do see that it has something to do with the yaml file when the task is running. saveToString to be exact. But I am still not seeing in the error message exactly why. The plugin will run flawlessly for days then for no reason it will just error out.

 

Caused by: java.lang.NullPointerException: Nodes must be provided.
at me.buyland.buyland.main.saveRentConfig(main.java:173)
So you try to save a null node in main.java at line 173. For more information: http://forums.bukkit.org/threads/ho...ubleshoot-your-own-plugins-by-yourself.32457/

 

Problem was that the yaml file had emptyed I am guessing from saving it to fast. I changed the time on the sync from 30 seconds to 1 min