Do you plan on updating this to 1.5, because currently, the GUI doesn't open in 1.5. If it helps, these are the stacktraces I got.

First On Load Error:

ReflectionTypeLoadException getting types in assembly BestApparel: System.Reflection.ReflectionTypeLoadException: Exception of type 'System.Reflection.ReflectionTypeLoadException' was thrown.
at (wrapper managed-to-native) System.Reflection.Assembly.GetTypes(System.Reflection.Assembly,bool)
at System.Reflection.Assembly.GetTypes () [0x00000] in <eae584ce26bc40229c1b1aa476bfa589>:0
at Verse.ModAssemblyHandler.AssemblyIsUsable (System.Reflection.Assembly asm) [0x00000] in <957a20e0be784a65bc32cf449445b937>:0

Loader exceptions:
=> System.TypeLoadException: Could not resolve type with token 0100005f (from typeref, class/assembly Verse.Dialog_Rename, Assembly-CSharp, Version=1.4.8509.26899, Culture=neutral, PublicKeyToken=null)

UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.ModAssemblyHandler:AssemblyIsUsable (System.Reflection.Assembly)
Verse.ModAssemblyHandler:ReloadAll ()
Verse.ModContentPack:ReloadContent (bool)
Verse.LoadedModManager:LoadModContent (bool)
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 ()

Second On Load Error:

Could not find a type named BestApparel.ui.BestApparelMainTabWindow
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch1 (string)
Verse.ParseHelper:ParseType (string)
Verse.ParseHelper:FromString<System.Type> (string)
Verse.DirectXmlToObject:ObjectFromXml<System.Type> (System.Xml.XmlNode,bool)
Verse.DirectXmlToObject:ObjectFromXmlReflection<System.Type> (System.Xml.XmlNode,bool)
Verse.DirectXmlToObject:ObjectFromXml<RimWorld.MainButtonDef> (System.Xml.XmlNode,bool)
Verse.DirectXmlToObject:ObjectFromXmlReflection<RimWorld.MainButtonDef> (System.Xml.XmlNode,bool)
Verse.DirectXmlLoader:DefFromNode (System.Xml.XmlNode,Verse.LoadableXmlAsset)
Verse.LoadedModManager:ParseAndProcessXML (System.Xml.XmlDocument,System.Collections.Generic.Dictionary`2<System.Xml.XmlNode, Verse.LoadableXmlAsset>,bool)
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 ()

When attempting to open the GUI:

Root level exception in OnGUI(): System.NullReferenceException: Object reference not set to an instance of an object
[Ref C4A54921]
at Verse.WindowStack.Add (Verse.Window window) [0x00000] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainTabsRoot.ToggleTab (RimWorld.MainButtonDef newTab, System.Boolean playSound) [0x0006b] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainButtonWorker_ToggleTab.Activate () [0x00005] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainButtonWorker.InterfaceTryActivate () [0x0008d] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainButtonWorker.DoButton (UnityEngine.Rect rect) [0x000ee] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainButtonsRoot.DoButtons () [0x00119] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.MainButtonsRoot.MainButtonsOnGUI () [0x0000e] in <957a20e0be784a65bc32cf449445b937>:0
at RimWorld.UIRoot_Play.UIRootOnGUI () [0x00037] in <957a20e0be784a65bc32cf449445b937>:0
at Verse.Root.OnGUI () [0x0003d] in <957a20e0be784a65bc32cf449445b937>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch1 (string)
Verse.Root:OnGUI ()