Description of problem:
adding virtualbox repofile and updating system via terminal

Version-Release number of selected component:
xfce4-panel-4.13.4-1.fc29

Additional info:
reporter:       libreport-2.9.7
backtrace_rating: 4
cmdline:        xfce4-panel --display :0.0 --sm-client-id 265861629-0b57-492d-88d3-6beba6893a62
crash_function: magazine_chain_pop_head
executable:     /usr/bin/xfce4-panel
journald_cursor: s=cc66409940884a46899b73ec568a4e63;i=1a584;b=8325ff7266ec4180ab8eae220b4859ad;m=f11b7ff;t=5809f025f151e;x=a2efa1e1b99ddbc8
kernel:         4.20.4-200.fc29.x86_64
rootdir:        /
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 magazine_chain_pop_head at gslice.c:538
 #1 thread_memory_magazine1_alloc at gslice.c:841
 #2 g_slice_alloc at gslice.c:1015
 #3 g_slice_alloc0 at gslice.c:1050
 #4 g_object_notify_queue_freeze at /usr/include/glib-2.0/gobject/gobjectnotifyqueue.c:79
 #5 gtk_widget_unparent at gtkwidget.c:4598
 #6 gtk_bin_remove at gtkbin.c:151
 #7 g_cclosure_marshal_VOID__OBJECTv at gmarshal.c:2102
 #8 _g_closure_invoke_va at gclosure.c:873
 #11 gtk_container_remove at gtkcontainer.c:1905