Вылет при удалении элемента управления

'==============================================================
' [ Улучшенное текстовое поле System.Windows.Forms.TextBox ]
'  Код написан: Kay Kokh - @dosx_plus (Telegram)
'
' Просьба сохранять авторство.
'==============================================================
 
 
Imports System.Runtime.CompilerServices
Imports System.Runtime.InteropServices
 
Public Class TextBoxPlus
    Inherits TextBox
    Dim Runtime As New Timer
    Property WaterMark As String = Nothing
    Property AcceptsCtrlBack As Boolean = True
    Sub New()
        Me.AcceptsTab = True
        AddHandler Runtime.Tick, AddressOf LoadSettings
        Runtime.Interval = 50
        Runtime.Start()
        Me.Update()
        Me.Focus()
    End Sub
 
    Sub LoadSettings()
        Me.SetWatermark(WaterMark)
    End Sub
 
    Private Sub CtrlBackspaceEvent(ByVal sender As Object, ByVal e As KeyEventArgs) Handles Me.KeyDown
        If AcceptsCtrlBack = True Then
            If Me.ReadOnly = False Then
                If e.Control AndAlso e.KeyCode = Keys.Back Then
                    e.SuppressKeyPress = True
                    If Me.SelectionStart > 0 Then
                        SendKeys.Send("+{LEFT}{DEL}")
                    End If
                End If
            End If
        End If
    End Sub
End Class
 
Module TextboxPlusWinAPI
    Private Const API_LIBRARY As String = "user32.dll"
    Private Const ECM_FIRST As UInteger = &H1500
    Private Const EM_SETCUEBANNER As UInteger = ECM_FIRST + 1
    <
        DllImport(
            API_LIBRARY,
            CharSet:=CharSet.Auto,
            SetLastError:=False
        )
    >
    Private Function SendMessage(
        ByVal hWnd As IntPtr,
        ByVal Msg As UInteger,
        ByVal wParam As UInteger,
    <
        MarshalAs(
            UnmanagedType.LPWStr
        )
    > ByVal lParam As String) As IntPtr
    End Function
    <
        Extension()
    >
    Sub SetWatermark(
        ByVal TXT As TextBox,
        ByVal WaterMarkTextString As String
    )
        SendMessage(
            TXT.Handle,
            EM_SETCUEBANNER,
            0,
            WaterMarkTextString
        )
    End Sub
End Module

Protected Overrides Sub OnHandleDestroyed(e As EventArgs)
'...
End Sub