Startup error with 1.5

[StellarHarbour]

Error while instantiating a mod of type MusicManager.MusicManager: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.TypeInitializationException: The type initializer for 'MusicManager.MusicManager' threw an exception. ---> System.ArgumentException: FieldRefAccess<Verse.SongDef> for RimWorld.MusicManagerPlay, lastStartedSong caused an exception ---> System.MissingFieldException: Field 'MusicManagerPlay.lastStartedSong' not found.
at HarmonyLib.AccessTools.FieldRefAccess[F] (System.Type type, System.String fieldName) [0x0002e] in <6ddb2f07a97745adaa7bad4e17020462>:0
--- End of inner exception stack trace ---
at HarmonyLib.AccessTools.FieldRefAccess[F] (System.Type type, System.String fieldName) [0x000cd] in <6ddb2f07a97745adaa7bad4e17020462>:0
at MusicManager.MusicManager..cctor () [0x00034] in :0
--- End of inner exception stack trace ---
at (wrapper managed-to-native) System.Reflection.MonoCMethod.InternalInvoke(System.Reflection.MonoCMethod,object,object[],System.Exception&)
at System.Reflection.MonoCMethod.InternalInvoke (System.Object obj, System.Object[] parameters) [0x00002] in :0
--- End of inner exception stack trace ---
at System.Reflection.MonoCMethod.InternalInvoke (System.Object obj, System.Object[] parameters) [0x00014] in :0
at System.Reflection.MonoCMethod.DoInvoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0007a] in :0
at System.Reflection.MonoCMethod.Invoke (System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in :0
at System.RuntimeType.CreateInstanceImpl (System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes, System.Threading.StackCrawlMark& stackMark) [0x00213] in :0
at System.Activator.CreateInstance (System.Type type, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes) [0x00095] in :0
at System.Activator.CreateInstance (System.Type type, System.Object[] args) [0x00000] in :0
at Verse.LoadedModManager.CreateModClasses () [0x00076] in <8b65cb0a4c2c41c5b3fbd3a92fbde076>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch0 (string)
Verse.LoadedModManager:CreateModClasses ()
Verse.LoadedModManager:LoadAllActiveMods (bool)
Verse.PlayDataLoader:DoPlayLoad ()
Verse.PlayDataLoader:LoadAllPlayData (bool)
Verse.Root/<>c:b__6_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c: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 ()