I have the same problem. Icecat segfaults right away without any window appearing. “-safe-mode” does not make a difference, but with “-p” I’m presented with the profile manager. I haven’t tried creating a new profile yet, nor have I tried deleting files from my existing profile.
I’m using Gnome on Guix System. To be sure that it isn’t caused by a known bug in how we packaged Gnome Shell, I unset LD_LIBRARY_PATH before running icecat, but with no effect. I see a segfault with the latest icecat-78.3.1-guix0-preview1 and with the older 78.3.0-guix0-preview1. No segfault with 68.12.0-guix0-preview1. -- Ricardo