Non-fatal assertion failure when opening and closing burn dialog

Output from starting the program and then opening and closing the burn dialog:

DBG[xfburn-main.c:270] main(): xfburn version 0.6.3git-67388ba for Xfce 4.16

DBG[xfburn-settings.c:275] load_settings(): parsed
** Message: 20:35:10.990: Using UDEV
DBG[xfburn-device-list.c:229] xfburn_device_list_init(): Constructing device list
DBG[xfburn-udev-manager.c:284] xfburn_udev_manager_get_devices(): Found writer 'Dell     DVD+/-RW DW316  ' at '/dev/sr0'
DBG[xfburn-device.c:435] xfburn_device_fillin_libburn_info(): libburn will determine BD support based on the disk in the drive
DBG[xfburn-device.c:443] xfburn_device_fillin_libburn_info(): Dell     DVD+/-RW DW316   can burn: 1 [cdr: 1, cdrw: 1, dvdr: 1, dvdram: 1]
DBG[xfburn-device.c:355] refresh_disc(): disc_status = 2
DBG[xfburn-device.c:361] refresh_disc(): profile_no = 0x0 (), NOT erasable
** Message: 20:35:11.151: Using gstreamer transcoder.
DBG[xfburn-device-box.c:518] check_disc_validity(): blank_mode = 0

(xfburn:761412): libxfce4ui-CRITICAL **: 20:35:12.340: xfce_titled_dialog_update_icon: assertion 'icon_name != NULL' failed

(xfburn:761412): libxfce4ui-CRITICAL **: 20:35:13.615: xfce_titled_dialog_update_icon: assertion 'icon_name != NULL' failed

Reproduced on both the current main branch and on 0.6.2 using Pop!_OS 22.04.