XML RimWorld.ThoughtDef defines the same field twice: nullifyingTraits.

Field contents: RKTrait_YunDanFengQing.

Whole XML:

<ThoughtDef><defName>SleptInBedroom</defName><durationDays>1</durationDays><stackLimit>1</stackLimit><stages><li><label>awful bedroom</label><description>I had to sleep in an awful room.</description><baseMoodEffect>-4</baseMoodEffect></li><li IsNull="True" /><li IsNull="True" /><li><label>decent bedroom</label><description>I got to sleep in a pretty decent bedroom.</description><baseMoodEffect>2</baseMoodEffect></li><li><label>slightly impressive bedroom</label><description>I got to sleep in a slightly impressive bedroom. I like it.</description><baseMoodEffect>3</baseMoodEffect></li><li><label>impressive bedroom</label><description>I slept in an impressive bedroom. It was great.</description><baseMoodEffect>4</baseMoodEffect></li><li><label>very impressive bedroom</label><description>I slept in a very impressive bedroom. I love it.</description><baseMoodEffect>5</baseMoodEffect></li><li><label>extremely impressive bedroom</label><description>I slept in an extremely impressive bedroom. It was marvelous.</description><baseMoodEffect>6</baseMoodEffect></li><li><label>unbelievably impressive bedroom</label><description>I slept in an unbelievably impressive bedroom. It was truly astounding.</description><baseMoodEffect>7</baseMoodEffect></li><li><label>wondrously impressive bedroom</label><description>I slept in a heavenly bedroom. It was wondrous.</description><baseMoodEffect>8</baseMoodEffect></li></stages><nullifyingTraits><li>PTD02sw</li><li>PTF02tyqs</li><li>RKTrait_YunDanFengQing</li></nullifyingTraits><nullifyingTraits><li>RKTrait_YunDanFengQing</li></nullifyingTraits></ThoughtDef>
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) Verse.Log:Verse.Log.Error_Patch2 (string)
XmlExtensions.CustomXmlLoader:ObjectFromXml<RimWorld.ThoughtDef> (System.Xml.XmlNode,bool,System.Xml.XmlNode,string)
XmlExtensions.CustomXmlLoader:ObjectFromXmlReflection<RimWorld.ThoughtDef> (System.Xml.XmlNode,bool)
(wrapper dynamic-method) Verse.DirectXmlLoader:Verse.DirectXmlLoader.DefFromNode_Patch3 (System.Xml.XmlNode,Verse.LoadableXmlAsset)
(wrapper dynamic-method) Verse.LoadedModManager:Verse.LoadedModManager.ParseAndProcessXML_Patch4 (System.Xml.XmlDocument,System.Collections.Generic.Dictionary`2<System.Xml.XmlNode, Verse.LoadableXmlAsset>)
Verse.LoadedModManager:LoadAllActiveMods ()
Verse.PlayDataLoader:DoPlayLoad ()
Verse.PlayDataLoader:LoadAllPlayData (bool)
Verse.Root/<>c:<Start>b__6_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__27_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()