When interfaces breaks, be more gentle

[rappen]

Now and then, I've seen these strange error, when a tool has interface IGitHubPlugin etc, and it breaks when trying to get the username/repository. The similar for PayPal, Help, etc.

Found when debugging:

Error Time: 2024-06-16 10:38:28.116
System.NullReferenceException
Object reference not set to an instance of an object.
XrmToolBox
at XrmToolBox.New.NewForm.GetGithubBaseUrl(String page)
   at XrmToolBox.New.NewForm.githubPluginMenuItem_Click(Object sender, EventArgs e)
   at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
   at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
   at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ToolStrip.WndProc(Message& m)
   at System.Windows.Forms.ToolStripDropDown.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 XrmToolBox.Program.Main(String[] args)

This PR will make XTB to be a bit nicer, since I couldn't find a way to solve this issue.

[MscrmTools]

The issue seems more related to ActiveControl being null, isn't it?

[rappen]

I have no idea how that happens, but it does, now and then... No pattern found yet.
When I have tried to reproduce it, I believe the dbMain.ActiveContent is not null, but it can't be cast as either PluginForm or IGitHubPlugin (in the example above, but similar for other interfaces too).