bug : rep_hist_note_dns_error: Non-fatal assertion

Happened in latest -git

May 12 18:56:32.000 [warn] tor_bug_occurred_(): Bug: src/feature/stats/rephist.c:328: rep_hist_note_dns_error: Non-fatal assertion !(!dns_stats) failed. (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug: Tor 0.4.7.0-alpha-dev (git-22861c2f4083e7e2): Non-fatal assertion !(!dns_stats) failed in rep_hist_note_dns_error at src/feature/stats/rephist.c:328. Stack trace: (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(log_backtrace_impl+0x5a) [0x5644503140ca] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(tor_bug_occurred_+0x173) [0x56445031f113] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(+0x1add9f) [0x5644503ecd9f] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/lib64/libevent-2.1.so.7(+0x2bc4d) [0x7f0726168c4d] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/lib64/libevent-2.1.so.7(+0x1f9dc) [0x7f072615c9dc] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/lib64/libevent-2.1.so.7(event_base_loop+0x53f) [0x7f072615d98f] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(do_main_loop+0xdd) [0x5644502a513d] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(tor_run_main+0x185) [0x5644502a0c25] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(tor_main+0x46) [0x56445029d276] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(main+0x19) [0x56445029ce29] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /lib64/libc.so.6(__libc_start_main+0xea) [0x7f0725ac7e3a] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:32.000 [warn] Bug:     /usr/bin/tor(_start+0x2a) [0x56445029ce7a] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] tor_bug_occurred_(): Bug: src/feature/stats/rephist.c:328: rep_hist_note_dns_error: Non-fatal assertion !(!dns_stats) failed. (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] Bug: Tor 0.4.7.0-alpha-dev (git-22861c2f4083e7e2): Non-fatal assertion !(!dns_stats) failed in rep_hist_note_dns_error at src/feature/stats/rephist.c:328. Stack trace: (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] Bug:     /usr/bin/tor(log_backtrace_impl+0x5a) [0x5644503140ca] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] Bug:     /usr/bin/tor(tor_bug_occurred_+0x173) [0x56445031f113] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] Bug:     /usr/bin/tor(+0x1add9f) [0x5644503ecd9f] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)
May 12 18:56:37.000 [warn] Bug:     /usr/lib64/libevent-2.1.so.7(+0x2bc4d) [0x7f0726168c4d] (on Tor 0.4.7.0-alpha-dev 22861c2f4083e7e2)

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