Program received signal SIGABRT, Aborted.
0x00007ffff5acc267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
55 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 0x00007ffff5acc267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
#1 0x00007ffff5acdeca in __GI_abort () at abort.c:89
#2 0x0000000000407914 in os_panic () at /home/otroan/src/vpp/build-data/../vpp/vnet/main.c:266
#3 0x00007ffff66ec978 in debugger () at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/error.c:81
#4 0x00007ffff66ecd88 in _clib_error (how_to_die=2, function_name=0x0, line_number=0, fmt=0x7ffff7272370 "%s:%d (%s) assertion `%s' fails")
at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/error.c:139
#5 0x00007ffff70a98fb in vnet_get_sw_interface (vnm=0x665980 <vnet_main>, sw_if_index=5)
at /home/otroan/src/vpp/build-data/../vnet/vnet/interface_funcs.h:49
#6 0x00007ffff70b307d in ip4_probe_neighbor (vm=0x665240 <vlib_global_main>, dst=0x7fffc53f949e, sw_if_index=5)
at /home/otroan/src/vpp/build-data/../vnet/vnet/ip/ip4_forward.c:2287
#7 0x000000000042e6f3 in resolver_process (vm=0x665240 <vlib_global_main>, rt=0x7fffc5684000, f=0x0) at /home/otroan/src/vpp/build-data/../vpp/api/api.c:704
#8 0x00007ffff753ebfd in vlib_process_bootstrap (_a=140736510655776) at /home/otroan/src/vpp/build-data/../vlib/vlib/main.c:1177
#9 0x00007ffff67016e0 in clib_calljmp () at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/longjmp.S:110
#10 0x00007fffc5b97cf0 in ?? ()
#11 0x00007ffff753ed27 in vlib_process_startup (vm=0x9858d0486e9ac100, p=0xffffffffffffffff, f=0x7fffc5684000)
at /home/otroan/src/vpp/build-data/../vlib/vlib/main.c:1201
#12 0x0000000000665358 in vlib_global_main ()

or with only IPv4
Program received signal SIGABRT, Aborted.
0x00007ffff5acc267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
55 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 0x00007ffff5acc267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
#1 0x00007ffff5acdeca in __GI_abort () at abort.c:89
#2 0x0000000000407914 in os_panic () at /home/otroan/src/vpp/build-data/../vpp/vnet/main.c:266
#3 0x00007ffff66ec978 in debugger () at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/error.c:81
#4 0x00007ffff66ecd88 in _clib_error (how_to_die=2, function_name=0x0, line_number=0, fmt=0x7ffff7272370 "%s:%d (%s) assertion `%s' fails")
at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/error.c:139
#5 0x00007ffff70a98fb in vnet_get_sw_interface (vnm=0x665980 <vnet_main>, sw_if_index=5)
at /home/otroan/src/vpp/build-data/../vnet/vnet/interface_funcs.h:49
#6 0x00007ffff70b307d in ip4_probe_neighbor (vm=0x665240 <vlib_global_main>, dst=0x7fffc54840da, sw_if_index=5)
at /home/otroan/src/vpp/build-data/../vnet/vnet/ip/ip4_forward.c:2287
#7 0x000000000042e6f3 in resolver_process (vm=0x665240 <vlib_global_main>, rt=0x7fffc5684000, f=0x0) at /home/otroan/src/vpp/build-data/../vpp/api/api.c:704
#8 0x00007ffff753ebfd in vlib_process_bootstrap (_a=140736510655776) at /home/otroan/src/vpp/build-data/../vlib/vlib/main.c:1177
#9 0x00007ffff67016e0 in clib_calljmp () at /home/otroan/src/vpp/build-data/../vppinfra/vppinfra/longjmp.S:110
#10 0x00007fffc5b97cf0 in ?? ()
#11 0x00007ffff753ed27 in vlib_process_startup (vm=0xa023438064492e00, p=0xffffffffffffffff, f=0x7fffc5684000)
at /home/otroan/src/vpp/build-data/../vlib/vlib/main.c:1201
#12 0x0000000000665358 in vlib_global_main ()

To reproduce, steps are something like:
r = vpp_papi.tap_connect(1, b'tap0\0', bytearray.fromhex('000000000000'), 0, 0)
r = vpp_papi.sw_interface_add_del_address(swifindex, is_add, is_ipv6, del_all, address_length, address)
r = vpp_papi.sw_interface_set_flags(swifindex, admin_up_down, link_up_down, deleted)
r = vpp_papi.ip_add_del_route(next_hop_sw_if_index, vrf_id, lookup_in_vrf, resolve_attempts, classify_table_index,
create_vrf_if_needed, resolve_if_needed, is_add, is_drop, is_ipv6, is_local,
is_classify, is_multipath, not_last, next_hop_weight, dst_address_length,
dst_address, next_hop_address)
r = vpp_papi.tap_delete(swifindex)

Where next-hop is out the TAP interface.