Been seeing this for quite some time and happens all the time out of nowhere (opening apps, loging out) thus turning WL in a shitshow.
(gdb) bt
#0 0x080de672 in e_exec_instance_watcher_del (inst=0x9b49040, func=0xa97aa45e <_bar_instance_watch>, data=0x9b4f138) at src/bin/e_exec.c:389
#1 0xa97aa68b in _bar_icon_del (inst=0x94b9098, ic=0x9b4f138) at src/modules/luncher/bar.c:204
#2 0xa97ad6a3 in _bar_cb_exec_del (data=0x0, type=265, ex=0x96dbfa0) at src/modules/luncher/bar.c:1139
#3 0xb6c5a650 in _ecore_call_handler_cb (func=0xa97ad4b3 <_bar_cb_exec_del>, data=0x0, type=265, event=0x96dbfa0) at lib/ecore/ecore_private.h:317
#4 0xb6c5b535 in _ecore_event_call () at lib/ecore/ecore_events.c:518
#5 0xb6c63dcd in _ecore_main_loop_iterate_internal (once_only=0) at lib/ecore/ecore_main.c:2359
#6 0xb6c61e8b in ecore_main_loop_begin () at lib/ecore/ecore_main.c:1287
#7 0x0807ba56 in main (argc=1, argv=0xbfc0f194) at src/bin/e_main.c:1093
(gdb)