Bad file descriptor when moving too fast in the cache

[bitbrain]

java.io.IOException: Bad file descriptor is thrown when moving too fast in different directions, because a chunk is saved which is currently loaded and vise versa:

java.io.IOException: Bad file descriptor
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:297)
    at java.io.ObjectOutputStream$BlockDataOutputStream.drain(ObjectOutputStream.java:1870)
    at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(ObjectOutputStream.java:1779)
    at java.io.ObjectOutputStream.writeNonProxyDesc(ObjectOutputStream.java:1283)
    at java.io.ObjectOutputStream.writeClassDesc(ObjectOutputStream.java:1228)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1424)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175)
    at java.io.ObjectOutputStream.writeFatalException(ObjectOutputStream.java:1570)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:350)
    at de.myreality.chunx.io.SimpleChunkSaver.save(SimpleChunkSaver.java:94)
    at de.myreality.chunx.caching.CachedChunkHandler.saveChunk(CachedChunkHandler.java:174)
    at de.myreality.chunx.caching.CachedChunkHandler.unloadChunk(CachedChunkHandler.java:192)
    at de.myreality.chunx.caching.CachedChunkHandler.unloadChunks(CachedChunkHandler.java:203)
    at de.myreality.chunx.caching.CachedChunkHandler.handleChunks(CachedChunkHandler.java:114)
    at de.myreality.chunx.caching.SimpleCachedChunkSystem.update(SimpleCachedChunkSystem.java:97)