SUMMARY

Sometimes, when I unplug my ethernet cable, the plasma-nm applet in the system tray disappears and then tries to load again in an infinite loop.

Today I noticed plasmashell was logging the following for every load attempt:

> qrc:/plasma/plasmoids/org.kde.plasma.networkmanagement/contents/ui/main.qml:82: TypeError: Cannot read property 'expanded' of null
> file:///usr/lib/qt/qml/QtQuick/Controls/Styles/Plasma/BusyIndicatorStyle.qml:39:9: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... }
In htop I can see a NetworkManager process being created and destroyed at the same rate as the applet. However, there are no signs of NetworkManager crashing, according to coredumpctl.

The only way to break the infinite loop is to run NetworkManager from the console. In particular, I run:

> sudo NetworkManager --no-daemon
After a few attempts (the command usually exits, probably due to there already being another NetworkManager process alive), NetworkManager stays running and so does the applet.

I wonder if there is something wrong with my system or the downstream software, since the applet keeps on trying to reach internet through the Ethernet port, which is listed as active even in ifconfig but is actually unplugged. I can overcome this by suspending and resuming the laptop.

Still, I find the scripting error at main.qml:82 very suspicious.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 5.19.0
KDE Frameworks Version: 5.70.0
Qt Version: 5.15.0
Kernel Version: 5.6.15-arch1-1
OS Type: 64-bit

ADDITIONAL INFORMATION
This was already an issue in older versions of Plasma and Qt for at least the last four months.

In my system there is no main.qml, but main.qmlc. If there is a way to use/compile a custom main.qml, please let me know.