Fix Control.Dispose crash when dependent UserControl fails to load due to missing assembly#13840

LeafShi1 merged 1 commit intodotnet:maindotnet/winforms:mainfrom

LeafShi1:Fix_13835_Add_defensive_null_checks_to_Control.DisposeLeafShi1/winforms:Fix_13835_Add_defensive_null_checks_to_Control.DisposeCopy head branch name to clipboard