Crash when opening any window

I wanted to try simula on my NixOS 22.05 machine but had no luck so far. I'm using the current master branch from simula.

1. First attempts were with an HTC vive connected, but I get VK_ERROR_INCOMPATIBLE_DRIVER errors when starting monado from the simula build. The headset works fine (xrgears and other demos) with several different versions of monado that I built separately, but using those with simula (by setting XR_RUNTIME_JSON) fails due to a glibc version mismatch. With some changes from the simula dev branch pulled in and the nixpkgs version set to the one my system config uses I had it somewhat working (a real Frankensteins Monster) but ran into the next issue (see below)
2. I abandoned the headset for now and just tried getting simula to start in the windowed mode. It immediately crashes. If I remove all the startup applications from config/config.dhall I get the blue sky background image and the i3status bar at the top. Once I start any application (terminal via Super+/) it crashes.

Log for the second problem is here output.file.txt. Maybe you can help me figure out the problem. I see the SESSION_MANAGER problem in the log, that's not in any of the existing github issues. The occurence corresponds to the moment I tried opening the terminal.

Start by reading the attached output.file.txt and reproducing the crash in windowed mode on the reported NixOS setup. Compare startup with and without applications in config/config.dhall, then focus on what changes when opening the terminal with Super+/. Done means Simula can open an application in windowed mode without crashing.