I get this error message after installing this mod:

[BetterLoading] Exception occurred processing mod finalize events! Details: System.TypeInitializationException: The type initializer for 'AppearanceClothes_AlienRacePatch.HarmonyPatches' threw an exception. ---> HarmonyLib.HarmonyException: Patching exception in method null ---> System.ArgumentException: Undefined target method for patch method static System.Void AppearanceClothes_AlienRacePatch.ITab_Pawn_AppearanceClothes_GetBodyTypeDefs_Patch::Postfix(Verse.Pawn pawn, System.Collections.Generic.List`1& __result)
at HarmonyLib.PatchClassProcessor.PatchWithAttributes (System.Reflection.MethodBase& lastOriginal) [0x0004d] in <2161c8330234450b8141397c32c11571>:0
at HarmonyLib.PatchClassProcessor.Patch () [0x00057] in <2161c8330234450b8141397c32c11571>:0
--- End of inner exception stack trace ---
at HarmonyLib.PatchClassProcessor.ReportException (System.Exception exception, System.Reflection.MethodBase original) [0x00127] in <2161c8330234450b8141397c32c11571>:0
at HarmonyLib.PatchClassProcessor.Patch () [0x00082] in <2161c8330234450b8141397c32c11571>:0
at HarmonyLib.Harmony.<PatchAll>b__10_0 (System.Type type) [0x00007] in <2161c8330234450b8141397c32c11571>:0
at HarmonyLib.CollectionExtensions.Do[T] (System.Collections.Generic.IEnumerable`1[T] sequence, System.Action`1[T] action) [0x00014] in <2161c8330234450b8141397c32c11571>:0
at HarmonyLib.Harmony.PatchAll (System.Reflection.Assembly assembly) [0x00006] in <2161c8330234450b8141397c32c11571>:0
at AppearanceClothes_AlienRacePatch.HarmonyPatches..cctor () [0x0000f] in <fdb4b6db3eca4f4bb1d2786b2d3bf17b>:0
--- End of inner exception stack trace ---
at (wrapper managed-to-native) System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(intptr)
at (wrapper dynamic-method) System.Runtime.CompilerServices.RuntimeHelpers.DMD<DMD<RunClassConstructor_Patch1>?569767168::RunClassConstructor_Patch1>(System.RuntimeTypeHandle)
at BetterLoading.Stage.InitialLoad.StageRunStaticCctors+<StaticConstructAll>d__16.MoveNext () [0x00062] in <5e8038a54c284c4daf4b8d85d57a8548>:0
Verse.Log:Error(String, Boolean)
BetterLoading.Stage.InitialLoad.<StaticConstructAll>d__16:MoveNext()
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)