Description of problem:
$ cat /etc/sysconfig/nftables.conf
table inet filter {
        include "/etc/nftables/customer/*"
}
$ mkdir -p /etc/nftables/customer
$ touch /etc/nftables/customer/f{00,01,02,03,04,05,06,07,08,09,10,11,12,13,14}
$ cat /etc/nftables/customer/f01
set s1 {
    type ipv4_addr
    flags constant,interval
}

set s2 {
    type ipv4_addr
    flags constant,interval
    elements = {
    1.1.1.1
    }
}
$ systemctl reload nftables

Version-Release number of selected component:
1:nftables-0.9.0-5.fc30

Additional info:
reporter:       libreport-2.10.0
backtrace_rating: 4
cmdline:        nft flush ruleset; include "/etc/sysconfig/nftables.conf";
crash_function: munmap_chunk
executable:     /usr/sbin/nft
journald_cursor: s=d895d7df2b0c4a2aace031882a2a98ef;i=9d539;b=6115920025684066aadbfaf9dbf15f32;m=a5b36b390f;t=58d68ab5f063c;x=174d4acda2b2dc2e
kernel:         5.1.15-300.fc30.x86_64
rootdir:        /
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (3 frames)
 #4 munmap_chunk at malloc.c:2840
 #5 scanner_destroy at scanner.l:900
 #6 nft_run_cmd_from_buffer at libnftables.c:469