[bugs] crash on a repetition edit


Got a crash with a fresh calcurse 4.2.0.

Steps to reproduce:

1. Create an appt.
2. Make it repetitive (e.g. every 2 days)
3. Edit repetition: delete "2" and hit enter (leaving the value as
an empty str):

Program received signal SIGABRT, Aborted.
0x00007ffff73bd785 in raise () from /lib/libc.so.6
(gdb) bt
#0  0x00007ffff73bd785 in raise () from /lib/libc.so.6
#1  0x00007ffff73bec05 in abort () from /lib/libc.so.6
#2  0x00007ffff73fae00 in __libc_message () from /lib/libc.so.6
#3  0x00007ffff74008fe in malloc_printerr () from /lib/libc.so.6
#4  0x00000000004349af in xfree (p=0x7fffffffe180) at mem.c:124
#5  0x000000000042aca2 in update_rept (rpt=0x4bab830, start=1544634000) at ui-day.c:328
#6  0x000000000042af1f in ui_day_item_edit () at ui-day.c:400
#7  0x00000000004039f2 in key_edit_item () at calcurse.c:152
#8  0x00000000004048fe in main (argc=1, argv=0x7fffffffe488) at calcurse.c:676


Vlad Glagolev <stealth@xxxxxxxxxxx>