Assertion `to_len >= 8' failed in convert_to_printable with optimizer trace enabled

CREATE TABLE t1 (f VARBINARY(16) NOT NULL, KEY(f));

INSERT INTO t1 VALUES ('a'),('b'); # Optional

SET optimizer_trace = 'enabled=on';

DELETE FROM t1 WHERE f = 'x';

# Cleanup

DROP TABLE t1;

mysqld: /data/src/10.4/sql/sql_string.cc:1154: uint convert_to_printable(char*, size_t, const char*, size_t, CHARSET_INFO*, size_t): Assertion `to_len >= 8' failed.

190617  1:35:47 [ERROR] mysqld got signal 6 ;

#7  0x00007fc2ef799f12 in __GI___assert_fail (assertion=0x56227fce69f0 "to_len >= 8", file=0x56227fce6820 "/data/src/10.4/sql/sql_string.cc", line=1154, function=0x56227fce6d40 <convert_to_printable(char*, unsigned long, char const*, unsigned long, charset_info_st const*, unsigned long)::__PRETTY_FUNCTION__> "uint convert_to_printable(char*, size_t, const char*, size_t, CHARSET_INFO*, size_t)") at assert.c:101

#8  0x000056227f194813 in convert_to_printable (to=0x7fc2e996898e "", to_len=5, from=0x7fc2d813a581 "x", from_len=1, from_cs=0x56228077c840 <my_charset_bin>, nbytes=0) at /data/src/10.4/sql/sql_string.cc:1154

#9  0x000056227f194a1b in String::append_semi_hex (this=0x7fc2e9968970, s=0x7fc2d813a581 "x", len=1, cs=0x56228077c840 <my_charset_bin>) at /data/src/10.4/sql/sql_string.cc:1206

#10 0x000056227f3ea826 in Field::print_key_value_binary (this=0x7fc2d813a5c0, out=0x7fc2e9968970, key=0x7fc2d813a581 "x", length=1) at /data/src/10.4/sql/field.cc:11298

#11 0x000056227f3ea708 in Field_varstring::print_key_value (this=0x7fc2d813a5c0, out=0x7fc2e9968970, length=16) at /data/src/10.4/sql/field.cc:11277

#12 0x000056227f58e46e in print_key_value (out=0x7fc2e99690a0, key_part=0x7fc2d813a768, key=0x7fc2d8068d90 "\001", used_length=18) at /data/src/10.4/sql/opt_range.cc:15861

#13 0x000056227f58dee3 in print_range (out=0x7fc2e99690a0, key_part=0x7fc2d813a768, range=0x7fc2e9968b30, n_key_parts=1) at /data/src/10.4/sql/opt_range.cc:15745

#14 0x000056227f58e1ad in trace_ranges (range_trace=0x7fc2e9969250, param=0x7fc2e9969500, idx=0, keypart=0x7fc2d8068e58, key_parts=0x7fc2d813a768) at /data/src/10.4/sql/opt_range.cc:15804

#15 0x000056227f57906b in get_key_scans_params (param=0x7fc2e9969500, tree=0x7fc2d8068dc0, index_read_must_be_used=false, update_tbl_stats=true, read_time=4.509765625) at /data/src/10.4/sql/opt_range.cc:7386

#16 0x000056227f56dc1d in SQL_SELECT::test_quick_select (this=0x7fc2d8013e60, thd=0x7fc2d8000b00, keys_to_use=..., prev_tables=0, limit=18446744073709551615, force_quick_range=false, ordered_output=false, remove_false_parts_of_where=false, only_single_index_range_scan=false) at /data/src/10.4/sql/opt_range.cc:2895

#17 0x000056227f1d52bc in SQL_SELECT::check_quick (this=0x7fc2d8013e60, thd=0x7fc2d8000b00, force_quick_range=false, limit=18446744073709551615) at /data/src/10.4/sql/opt_range.h:1653

#18 0x000056227f5b5102 in mysql_delete (thd=0x7fc2d8000b00, table_list=0x7fc2d80131f0, conds=0x7fc2d8013a50, order_list=0x7fc2d80054a0, limit=18446744073709551615, options=0, result=0x0) at /data/src/10.4/sql/sql_delete.cc:543

#19 0x000056227f0caa83 in mysql_execute_command (thd=0x7fc2d8000b00) at /data/src/10.4/sql/sql_parse.cc:4713

#20 0x000056227f0d5ab1 in mysql_parse (thd=0x7fc2d8000b00, rawbuf=0x7fc2d8013108 "DELETE FROM t1 WHERE f = 'x'", length=28, parser_state=0x7fc2e996b180, is_com_multi=false, is_next_command=false) at /data/src/10.4/sql/sql_parse.cc:7887

#21 0x000056227f0c1dcd in dispatch_command (command=COM_QUERY, thd=0x7fc2d8000b00, packet=0x7fc2d8008311 "DELETE FROM t1 WHERE f = 'x'", packet_length=28, is_com_multi=false, is_next_command=false) at /data/src/10.4/sql/sql_parse.cc:1829

#22 0x000056227f0c058b in do_command (thd=0x7fc2d8000b00) at /data/src/10.4/sql/sql_parse.cc:1362

#23 0x000056227f23971b in do_handle_one_connection (connect=0x56228301c010) at /data/src/10.4/sql/sql_connect.cc:1403

#24 0x000056227f23947f in handle_one_connection (arg=0x56228301c010) at /data/src/10.4/sql/sql_connect.cc:1306

#25 0x000056227fb63d73 in pfs_spawn_thread (arg=0x5622830513a0) at /data/src/10.4/storage/perfschema/pfs.cc:1862

#26 0x00007fc2f130e4a4 in start_thread (arg=0x7fc2e996c700) at pthread_create.c:456

#27 0x00007fc2ef856d0f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97