Install gnome-panel and start it from console, observe segfault. 

Backtrace:
Thread 1 "gnome-panel" received signal SIGSEGV, Segmentation fault.
0x0000000000000005 in ?? ()
(gdb) bt
#0  0x0000000000000005 in ??? ()
#1  0x00007ffff7d381d5 in XInternAtom
    (dpy=0x5555555b8260, name=name@entry=0x55555558ac2c "_GNOME_PANEL_ACTION", onlyIfExists=onlyIfExists@entry=0)
    at /usr/src/debug/libX11-1.8.7-1.fc39.x86_64/src/IntAtom.c:175
#2  0x00005555555763ff in gp_action_protocol_init
    (self=0x55555571b3d0 [GpActionProtocol])
    at /usr/src/debug/gnome-panel-3.50.0-2.fc39.x86_64/gnome-panel/panel-action-protocol.c:137
#3  0x00007ffff7c785ea in g_type_create_instance
    (type=0x555555602ac0 [GpActionProtocol]) at ../gobject/gtype.c:1997
#4  0x00007ffff7c5dfb4 in g_object_new_internal
    (class=0x55555563a040, params=0x0, n_params=0) at ../gobject/gobject.c:2245
#5  0x00007ffff7c5f5d6 in g_object_new_internal
    (n_params=<optimized out>, params=<optimized out>, class=<optimized out>)
    at ../gobject/gobject.c:2242
#6  g_object_new_with_properties
    (object_type=<optimized out>, n_properties=<optimized out>, names=names@entry=0x0, values=values@entry=0x0) at ../gobject/gobject.c:2408
#7  0x00007ffff7c60581 in g_object_new
    (object_type=<optimized out>, first_property_name=first_property_name@entry=0x0) at ../gobject/gobject.c:2054
#8  0x0000555555573119 in gp_action_protocol_new
--Type <RET> for more, q to quit, c to continue without paging--
    (application=0x55555578c580 [GpApplication])
    at /usr/src/debug/gnome-panel-3.50.0-2.fc39.x86_64/gnome-panel/panel-action-protocol.c:159
#9  gp_application_init (self=0x55555578c580 [GpApplication])
    at /usr/src/debug/gnome-panel-3.50.0-2.fc39.x86_64/gnome-panel/gp-application.c:412
#10 0x00007ffff7c785ea in g_type_create_instance (type=0x55555578c220 [GpApplication]) at ../gobject/gtype.c:1997
#11 0x00007ffff7c5dfb4 in g_object_new_internal (class=0x55555578c460, params=0x0, n_params=0) at ../gobject/gobject.c:2245
#12 0x00007ffff7c60470 in g_object_new_internal (n_params=0, params=0x0, class=0x55555578c460) at ../gobject/gobject.c:2540
#13 g_object_new_valist
    (object_type=object_type@entry=0x55555578c220 [GpApplication], first_property_name=first_property_name@entry=0x0, var_args=var_args@entry=0x7fffffffd340) at ../gobject/gobject.c:2604
#14 0x00007ffff72a9a6b in g_initable_new_valist
    (object_type=0x55555578c220 [GpApplication], first_property_name=0x0, var_args=var_args@entry=0x7fffffffd340, cancellable=cancellable@entry=0x0, error=error@entry=0x7fffffffd420) at ../gio/ginitable.c:246
#15 0x00007ffff72a9b6b in g_initable_new
    (object_type=<optimized out>, cancellable=cancellable@entry=0x0, error=error@entry=0x7fffffffd420, first_property_name=first_property_name@entry=0x0) at ../gio/ginitable.c:164
#16 0x000055555556e747 in gp_application_new (error=0x7fffffffd420)
    at /usr/src/debug/gnome-panel-3.50.0-2.fc39.x86_64/gnome-panel/gp-application.c:428
Python Exception <class 'gdb.error'>: value has been optimized out


Reproducible: Always

Steps to Reproduce:
1. Install gnome-panel 3.50.0
2. start gnome-panel from console and see segfault
3.
Actual Results:  
segfault

Expected Results:  
should start and allow me to modify the app list