Regression, randomly a heap assertion is triggered when closing the taskmgr from the performance tab

Okay, I got this two times now already within just half an hour usage of master head.
In two fresh installations.

A heap assertion when closing the taskmgr.
The 2nd time was with unmodified master head sources of 0.4.15-dev-3723-g8d70159 gcc8.4.0 RosBE-Win 2.2.1 selfbuilt iso.

0.4.15-dev-3723-g8d70159_heapAssert.png
0.4.15-dev-3723-g8d70159_heapAssert.log
I translated the backtrace, but Thomas recommended to use DPH, which I did not yet.

But the thing seems to be kind of reproducible.
Also a 0.4.15-dev-xxx regression for sure!