Applications with a zero-sized panel icon should use a fallback icon instead of displaying nothing

[Buggfix42]

Title pretty much says it. If a broken application registers a panel/window icon with a zero dimension Cinnamon will currently display a way to small "icon box" that is hardly clickable and almost unseeable.
This isn't a bug, it's rather bad handling of buggy applications. That's why I'm positing it here.
The broken application is "LMStudio". This is what it looks like when I hover the "icon box":

The output of xprop contains those relevant lines:

WM_STATE(WM_STATE):
		icon window: 0x0
_NET_WM_ICON(CARDINAL) = 

The expected behavior is of course to show the default/fallback "configuration icon" that's displayed when an application doesn't have a panel/window icon.

Mint 22.1
Cinnamon 6.4.8

[mtwebster]

I can't reproduce this with the LMStudio flatpak in Mint 22.3 (6.6) or our current muffin/cinnamon development versions (6.7.x).

Both of our 'stock' window list applets show the correct icon:

Is this a third-party window-list applet? It's also possible this has been fixed since your 6.4.8 version.

[Buggfix42]

@mtwebster Don't get me wrong, I don't need assistance in fixing this issue (a quick reinstall should do the trick).
I'm pointing out that Cinnamon could improve its handling with buggy applications.
A quick check for the icon's dimensions and then falling back to the default icon in case of a zero dimension would improve UX.
Buggy applications will always be there and if not for LM Studio, then for some other application.

[mtwebster]

You're assuming we haven't already addressed the issue. My testing suggests we have. We don't backport new Cinnamon releases (or non-critical fixes) to old Mint versions.

If you encounter the issue in a current Cinnamon version we can re-open this.

[Buggfix42]

I let a LLM generate code to register a zero-sized panel icon in two ways but turns out that in both cases I see the default configuration icon as a fallback.
That's weird. How did LM Studio manage to register a zero-sized panel icon without Cinnamon falling back to the default icon?
Since I already uninstalled the faulty installation I can't figure that out now.
I tried to replicate this bug by using a .desktop file in ~/.local/share/applications with an invalid icon file path and while it does not fallback to the default configuration icon (transparent background), the panel icon box is normal-sized unlike the LM Studio case. So no success.
It seems like I really did encounter a rare edge-case bug, so I'll not track this further than here.