It would be nice if errors in the debug console showed the stack trace as well as the error message.
For a function f(...) that produces an error, you can get the stack trace with this code:
xpcall(function() return f(...) end, debug.traceback)
However, it can be a pain to type this out every time you want a stack trace, and newer coders might not be aware that this feature of Lua exists. And in my experience, if you get an error in the debug console, more often than not you want to see the stack trace.
If screen real estate is thought to be a problem then the stack trace could be collapsible, but personally I don't think any extra formatting is necessary.