C# Bunifu UI System.NullReferenceException was unhandled

Question

I'm using Bunifu UI Framework, everything was fine until I added an "Exit" button from the Bunifu UI which is bunifuFlatButton, I tried both this.Close(); and Close(); and with both I'm getting System.NullReferenceException was unhandled Error.

Button:

Error:

System.NullReferenceException was unhandled
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=Bunifu_UI_v1.5.3
  StackTrace:
       at Bunifu.Framework.UI.BunifuFlatButton.method_5()
       at Bunifu.Framework.UI.BunifuFlatButton.BunifuFlatButton_MouseClick(Object sender, MouseEventArgs e)
       at System.Windows.Forms.Control.OnMouseClick(MouseEventArgs e)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.Label.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at Project.Program.Main() in C:\Project\Project\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

Thank you

Answer 1

I think that this happens because bunifu buttons have some methods like "change color on hover, color on mouse click etc" ,
when you click the button , the form closes, but then maybe the app tries to call a method on that bunifu button like for example change color after mouse click, but the form is closed, and then the error happens.
I fixed this by disabling the button before form close:

private void bunifuFlatButton1_Click(object sender, EventArgs e)
{
    bunifuFlatButton1.Enabled = false;
    this.Close();
}

Answer 2

Yeah currently there's an issue with Bunifu Flat Button . You can however use (as I have always done in such design use-cases) a Bunifu Thin Button or even better, a Bunifu Image Button if you'd wish to set an "Exit" button with an image only.