Debugger reliably crashes while stepping through instantiating Deskbar add-ons

[anevilyak]

If one steps into instantiate_object() and then attempts to step into the actual call to the instantiation function, Debugger reliably crashes in the thread handler where the top frame of the stack appears to have a NULL image pointer. Needs investigation.

[anevilyak]

After some brief digging, what appears to happen is:

• We single step until we're inside the instantiation function.
• The thread handler asks for the topmost frame to determine if it needs to continue stepping.
• The instruction pointer is at this point within the image of the add-on in question based on a listimage of the team being debugged.
• However, resolving that instruction pointer to an image fails, which is odd since that image has long since been loaded at this point. This suggests a problem adding the image to the list when notified of it being loaded, or an error while loading its debug information. Will dig further later.

[anevilyak]

Fixed in hrev44304.