Running on 64 bit Windows with 16 GB RAM 
Version: v1.14.5 (Stable)1/5/2021 2:41:53 PM: Critical error occurred
System.MissingMethodException: Method not found: 'Boolean Vintagestory.GameContent.BlockEntityAnvil.get_IsIronBloom()'.
   at gehelvehammer.src.GEBlockEntityAnvil.OnHelveHammerHitPatch(BlockEntityAnvil& __instance)
   at Vintagestory.GameContent.BlockEntityAnvil.OnHelveHammerHit_Patch4(BlockEntityAnvil this)
   at Vintagestory.GameContent.Mechanics.BEHelveHammer.get_Angle()
   at Vintagestory.GameContent.HelveHammerRenderer.OnRenderFrame(Single deltaTime, EnumRenderStage stage)
   at Vintagestory.Client.NoObf.ClientEventManager.TriggerRenderStage(EnumRenderStage stage, Single dt)
   at Vintagestory.Client.NoObf.ClientMain.TriggerRenderStage(EnumRenderStage stage, Single dt)
   at Vintagestory.Client.NoObf.ClientMain.MainRenderLoop(Single dt)
   at Vintagestory.Client.NoObf.ClientMain.MainGameLoop(Single deltaTime)
   at _Vq7Xo4xIdbZDwh8iDcGnovGKH7D._5RNBrkQoxljreqLqfZ3LUVDaIrr(Single )
   at _7KGTxxuvfNubJZCLAMEMJZBkPDeA._07k4LSTgxALpYbS1S6K07SItFcH(Single )
   at _7KGTxxuvfNubJZCLAMEMJZBkPDeA._aysJzMcCvicDqo8MC3TmjcDsfdZ(Single )
   at Vintagestory.Client.NoObf.ClientPlatformWindows.window_RenderFrame(Object sender, FrameEventArgs e)
   at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
   at OpenTK.GameWindow.RaiseRenderFrame(Double elapsed, Double& timestamp)
   at OpenTK.GameWindow.DispatchRenderFrame()
   at OpenTK.GameWindow.Run(Double updates_per_second, Double frames_per_second)
   at _4eRDDOqtbaPbgjN2dJ1zzD1FCRy._ExJp6VhLWG4xQoHsVn72tgyNbeG(_bWl72q5sGuTQypu8W8r7cRXUcRF , String[] )
   at _XKAWv6MyciUiZmECUonQCwPaCwE._ExJp6VhLWG4xQoHsVn72tgyNbeG(ThreadStart )
-------------------------------

Event Log, last 3 entries
==================================
{ TimeGenerated = 1/5/2021 2:41:53 PM, Site = , Source = .NET Runtime, Message = Application: Vintagestory.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: exception code c0020001, exception address 00007FFBD142A719
Stack:
 }
{ TimeGenerated = 1/5/2021 2:35:30 PM, Site = , Source = .NET Runtime, Message = Application: Vintagestory.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.MissingMethodException
   at gehelvehammer.src.GEBlockEntityAnvil.OnHelveHammerHitPatch(Vintagestory.GameContent.BlockEntityAnvil ByRef)
   at DynamicClass.Vintagestory.GameContent.BlockEntityAnvil.OnHelveHammerHit_Patch2(Vintagestory.GameContent.BlockEntityAnvil)
   at Vintagestory.GameContent.Mechanics.BEHelveHammer.get_Angle()
   at Vintagestory.GameContent.HelveHammerRenderer.OnRenderFrame(Single, Vintagestory.API.Client.EnumRenderStage)
   at Vintagestory.Client.NoObf.ClientEventManager.TriggerRenderStage(Vintagestory.API.Client.EnumRenderStage, Single)
   at Vintagestory.Client.NoObf.ClientMain.TriggerRenderStage(Vintagestory.API.Client.EnumRenderStage, Single)
   at Vintagestory.Client.NoObf.ClientMain.MainRenderLoop(Single)
   at Vintagestory.Client.NoObf.ClientMain.MainGameLoop(Single)
   at _uWwiuXC8cGTH1JnsWiUY9FUaXOo._0WtXQJqGAidcdKMfPHF0OxDIauE(Single)
   at _ydpin5JFjepNgd3JOZRb2z5I5Fg._LvRZFcsDWyPwKLB1F2UK7fQ2N6d(Single)
   at _ydpin5JFjepNgd3JOZRb2z5I5Fg._GO2qaUrk9dl0IceTLiA7P4LcpAB(Single)
   at Vintagestory.Client.NoObf.ClientPlatformWindows.window_RenderFrame(System.Object, OpenTK.FrameEventArgs)
   at System.EventHandler`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].Invoke(System.Object, System.__Canon)
   at OpenTK.GameWindow.RaiseRenderFrame(Double, Double ByRef)
   at OpenTK.GameWindow.DispatchRenderFrame()
   at OpenTK.GameWindow.Run(Double, Double)
   at _Ine8FeGTtDXciSIfaZMHMwCLKGBA._8puLW8J44fiq3A5hthQTfB8WNxc(_SbVlAI6dJIZ4JRt0da0lu23DF14, System.String[])
   at _lErb0L2e9E9htuT2VVnAsXIZqc7A._8puLW8J44fiq3A5hthQTfB8WNxc(System.Threading.ThreadStart)

 }
{ TimeGenerated = 1/5/2021 2:29:53 PM, Site = , Source = .NET Runtime, Message = Application: Vintagestory.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.MissingMethodException
   at gehelvehammer.src.GEBlockEntityAnvil.OnHelveHammerHitPatch(Vintagestory.GameContent.BlockEntityAnvil ByRef)
   at DynamicClass.Vintagestory.GameContent.BlockEntityAnvil.OnHelveHammerHit_Patch2(Vintagestory.GameContent.BlockEntityAnvil)
   at Vintagestory.GameContent.Mechanics.BEHelveHammer.get_Angle()
   at Vintagestory.GameContent.HelveHammerRenderer.OnRenderFrame(Single, Vintagestory.API.Client.EnumRenderStage)
   at Vintagestory.Client.NoObf.ClientEventManager.TriggerRenderStage(Vintagestory.API.Client.EnumRenderStage, Single)
   at Vintagestory.Client.NoObf.ClientMain.TriggerRenderStage(Vintagestory.API.Client.EnumRenderStage, Single)
   at Vintagestory.Client.NoObf.ClientMain.MainRenderLoop(Single)
   at Vintagestory.Client.NoObf.ClientMain.MainGameLoop(Single)
   at _uWwiuXC8cGTH1JnsWiUY9FUaXOo._0WtXQJqGAidcdKMfPHF0OxDIauE(Single)
   at _ydpin5JFjepNgd3JOZRb2z5I5Fg._LvRZFcsDWyPwKLB1F2UK7fQ2N6d(Single)
   at _ydpin5JFjepNgd3JOZRb2z5I5Fg._GO2qaUrk9dl0IceTLiA7P4LcpAB(Single)
   at Vintagestory.Client.NoObf.ClientPlatformWindows.window_RenderFrame(System.Object, OpenTK.FrameEventArgs)
   at System.EventHandler`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].Invoke(System.Object, System.__Canon)
   at OpenTK.GameWindow.RaiseRenderFrame(Double, Double ByRef)
   at OpenTK.GameWindow.DispatchRenderFrame()
   at OpenTK.GameWindow.Run(Double, Double)
   at _Ine8FeGTtDXciSIfaZMHMwCLKGBA._8puLW8J44fiq3A5hthQTfB8WNxc(_SbVlAI6dJIZ4JRt0da0lu23DF14, System.String[])
   at _lErb0L2e9E9htuT2VVnAsXIZqc7A._8puLW8J44fiq3A5hthQTfB8WNxc(System.Threading.ThreadStart)

 }