Created attachment 116610 [details]
Backtrace log

Hello,

This is a weird bug I don't know how to reproduce. However, it has already happened to me twice.

Sometimes, when clicking on a group of windows in the taskbar, the list of windows fails to generate and an empty small square appears instead. I haven't tried clicking inside the square. The crash doesn't happen until you repeteadly click on the group in the taskbar cause the square to appear and disappear a number of times (probably less than 10).

I was able to attach gdb to plasmashell before it crashed and got the backtrace. I'm attaching it.

Here is the system information provided by Info Center:

Operating System: Arch Linux 
KDE Plasma Version: 5.14.4
Qt Version: 5.11.2
KDE Frameworks Version: 5.52.0
Kernel Version: 4.19.4-arch1-1-ARCH
OS Type: 64-bit
Processor: 1 × Intel® Core™ i3-3110M CPU @ 2.40GHz
Memory: 7,7 GiB of RAM

Please do not hesitate to ask for any more information you need.

Thank you very much.