Looking at the corefile in the sosreport attached, we see the crash is here:

   │85        if (!xdp_impl_permission_store_call_lookup_sync (get_permission_store (),
   │86                                                         TABLE_NAME,
   │87                                                         "inhibit",
   │88                                                         &out_perms,
   │89                                                         &out_data,
   │90                                                         NULL,
   │91                                                         &error))
   │92          {
  >│93            g_warning ("Error getting permissions: %s", error->message);
   │94            g_clear_error (&error);
   │95          }

This means xdp_impl_permission_store_call_lookup_sync is failing without setting an error.
In other words, it's getting passed an invalid input.  Indeed, get_permission_store()
is returning NULL:

(gdb) p permission_store
$1 = (XdpImplPermissionStore *) 0x0

This will return NULL if it can't get a proxy to the org.freedesktop.impl.portal.PermissionStore service.
That service file is so:

[D-BUS Service]
Name=org.freedesktop.impl.portal.PermissionStore
Exec=@libexecdir@/xdg-permission-store
SystemdService=xdg-permission-store.service

So it will try to activate the systemd service associated with the dbus name.  but we don't have a user bus and we don't have systemd --user → fail.

I think we should just patch out SystemdService= from the service file.   and maybe fix dbus to ignore SystemdService for non-system-services

Created attachment 1349548 [details]
patch vbenes is testing

just threw this scratch build:

https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=14502327

to vbenes.  it has the above patch

Created attachment 1350096 [details]
latest version of the patch

this is the latest version of the patch, but now i'm wondering if the parts that remove the -SystemdService= are needed, or if it's really just the missing rpaths from the later hunks in the patch.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0767