MoopleDEV java.lang.nullpointerexception

I'm always getting this error. Someone can help me to fix it?
Using moopledev with CentOS

Code:

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java.lang.NullPointerException
    at com.sun.org.apache.xerces.internal.dom.ParentNode.nodeListItem(ParentNode.java:786)
    at com.sun.org.apache.xerces.internal.dom.ParentNode.item(ParentNode.java:800)
    at provider.wz.XMLDomMapleData.getChildren(XMLDomMapleData.java:99)
    at server.quest.MapleQuestRequirement.check(MapleQuestRequirement.java:72)
    at server.quest.MapleQuest.canComplete(MapleQuest.java:152)
    at client.MapleCharacter.mobKilled(MapleCharacter.java:2877)
    at server.life.MapleMonster.giveExpToCharacter(MapleMonster.java:284)
    at server.life.MapleMonster$SingleAttackerEntry.killedMob(MapleMonster.java:863)
    at server.life.MapleMonster.killBy(MapleMonster.java:300)
    at server.maps.MapleMap.killMonster(MapleMap.java:650)
    at server.maps.MapleMap.killMonster(MapleMap.java:559)
    at server.maps.MapleMap.damageMonster(MapleMap.java:551)
    at net.server.channel.handlers.AbstractDealDamageHandler.applyAttack(AbstractDealDamageHandler.java:366)
    at net.server.channel.handlers.MagicDamageHandler.handlePacket(MagicDamageHandler.java:56)
    at net.MapleServerHandler.messageReceived(MapleServerHandler.java:124)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.messageReceived(DefaultIoFilterChain.java:716)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:434)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:46)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:796)
    at org.apache.mina.filter.codec.ProtocolCodecFilter$ProtocolDecoderOutputImpl.flush(ProtocolCodecFilter.java:427)
    at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecFilter.java:245)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:434)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:46)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:796)
    at org.apache.mina.core.filterchain.IoFilterAdapter.messageReceived(IoFilterAdapter.java:119)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:434)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.fireMessageReceived(DefaultIoFilterChain.java:426)
    at org.apache.mina.core.polling.AbstractPollingIoProcessor.read(AbstractPollingIoProcessor.java:715)
    at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:668)
    at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:657)
    at org.apache.mina.core.polling.AbstractPollingIoProcessor.access$600(AbstractPollingIoProcessor.java:68)
    at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.run(AbstractPollingIoProcessor.java:1141)
    at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:64)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)

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Thanks