validator_logv appears to have an invalid name

I've had main crash twice with this assertion.

Thread 3 Crashed:
0   libsystem_kernel.dylib        	       0x198d4c704 __pthread_kill + 8
1   libsystem_pthread.dylib       	       0x198d83c28 pthread_kill + 288
2   libsystem_c.dylib             	       0x198c91ae8 abort + 180
3   named                         	       0x10406d728 assertion_failed + 408 (main.c:234)
4   libisc-9.19.23-dev.dylib      	       0x10425def8 isc_assertion_failed + 56 (assertions.c:48)
5   libdns-9.19.23-dev.dylib      	       0x104747e34 dns_name_totext + 112 (name.c:1038)
6   libdns-9.19.23-dev.dylib      	       0x10474b258 dns_name_format + 120 (name.c:1940)
7   libdns-9.19.23-dev.dylib      	       0x1048b2464 validator_logv + 364 (validator.c:3488)
8   libdns-9.19.23-dev.dylib      	       0x1048aa45c validator_log + 112 (validator.c:3510)
9   libdns-9.19.23-dev.dylib      	       0x1048af860 validate_answer_finish + 108 (validator.c:1642)
10  libdns-9.19.23-dev.dylib      	       0x1048aeeac validate_answer_signing_key_done + 136 (validator.c:1566)
11  libisc-9.19.23-dev.dylib      	       0x1042ab460 isc__after_work_cb + 144 (work.c:42)
12  libuv.1.dylib                 	       0x10442aff0 uv__work_done + 192
13  libuv.1.dylib                 	       0x10442e3c4 uv__async_io + 320
14  libuv.1.dylib                 	       0x10443e1e0 uv__io_poll + 1748
15  libuv.1.dylib                 	       0x10442e7bc uv_run + 244
16  libisc-9.19.23-dev.dylib      	       0x104280f54 loop_thread + 372 (loop.c:284)
17  libisc-9.19.23-dev.dylib      	       0x1042a0078 thread_body + 88 (thread.c:85)
18  libisc-9.19.23-dev.dylib      	       0x1042a0370 thread_run + 32 (thread.c:100)
19  libsystem_pthread.dylib       	       0x198d83fa8 _pthread_start + 148
20  libsystem_pthread.dylib       	       0x198d7eda0 thread_start + 8