Fix GUI error visibility by displaying new messages at bottom

[Arnav05-cyber]

• Changed _OutputWidgetHandler.emit() to append new messages to the end
• This ensures errors and new log messages appear at the bottom where they're more visible
• Fixes issue where errors could be hidden when appearing at the top of log window

Fixes: GUI error visibility issue

[dylansdaniels]

Hi, @Arnav05-cyber. Thanks for your PR. We actually decided to have the latest messages displayed at the top because of how the log automatically scrolls to the top. This ensures users actually see the latest messages as they are printed to the log in real time. So this is actually an intended behavior, not an error :)

[asoplata]

As Dylan said, this is actually the opposite of what we want: it would be better if errors were printed to the top of the log like other log information is, instead of everything being printed at the bottom: #1163 . If we want to change this PR such that it is about printing errors at the top instead of the bottom, then we can keep it open.

[dylansdaniels]

@asoplata I believe this is how it works already, though. So I don't think any change is needed

[asoplata]

True Python errors (such as errors during simulation time) appear to go on the bottom, as far as I've been able to tell. I've listed an example here: #1163 (comment)

[dylansdaniels]

I see, good catch. We definitely want those printed at the top as well