Got this error:

[Medieval - Vanilla - Start of stack trace]
Verse.PatchOperationReplace(xpath="/Defs/ThingDef[defName = "VCEF_AbyssalEel"]/techLevel"): Failed to find a node with the given xpath
Verse.PatchOperationSequence: Error in the operation at position=1
Verse.PatchOperationFindMod(Alpha Biomes): Error in <match>
[End of stack trace]
The top operation is the one that failed, the ones below it are the parents
Source file: C:\Program Files (x86)\Steam\steamapps\workshop\content\294100\2011469982\Patches\AlphaBiomesPatch.xml

UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch6 (string)
XmlExtensions.ErrorManager:PrintErrors (string,Verse.ModContentPack)
XmlExtensions.PatchOperation_Patch:Postfix (Verse.PatchOperation,bool&,System.Xml.XmlDocument)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.PatchOperation.Apply_Patch2 (Verse.PatchOperation,System.Xml.XmlDocument)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.LoadedModManager.ApplyPatches_Patch4 (System.Xml.XmlDocument,System.Collections.Generic.Dictionary`2<System.Xml.XmlNode, Verse.LoadableXmlAsset>)
Verse.LoadedModManager:LoadAllActiveMods (bool)
Verse.PlayDataLoader:DoPlayLoad ()
Verse.PlayDataLoader:LoadAllPlayData (bool)
Verse.Root/<>c:<Start>b__6_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_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 ()