Crash when EXPLAIN SELECT .. INTO row_sp_variable.field

DELIMITER $$

BEGIN NOT ATOMIC

  DECLARE a ROW(a INT);

  EXPLAIN SELECT 1 INTO a.a;

END;

$$

DELIMITER ;

#0  0x00007ffff5bcfa28 in raise () from /lib64/libc.so.6

#1  0x00007ffff5bd162a in abort () from /lib64/libc.so.6

#2  0x00007ffff5bc8227 in __assert_fail_base () from /lib64/libc.so.6

#3  0x00007ffff5bc82d2 in __assert_fail () from /lib64/libc.so.6

#4  0x0000555555b93179 in parse_sql (thd=0x7ffe6c000a98, 

    parser_state=0x7ffff0c1e140, creation_ctx=0x0, do_pfs_digest=true)

    at /home/bar/maria-git/server.10.2-ext/sql/sql_parse.cc:9931

#5  0x0000555555b8e50e in mysql_parse (thd=0x7ffe6c000a98, 

    rawbuf=0x7ffe6c0113b0 "BEGIN NOT ATOMIC\n  DECLARE a ROW(a INT);\n  EXPLAIN SELECT 1 INTO a.a;\nEND", length=73, parser_state=0x7ffff0c1e140, 

    is_com_multi=false, is_next_command=false)

    at /home/bar/maria-git/server.10.2-ext/sql/sql_parse.cc:7839

#6  0x0000555555b7c2dd in dispatch_command (command=COM_QUERY, 

    thd=0x7ffe6c000a98, 

    packet=0x7ffe6c007f99 "BEGIN NOT ATOMIC\n  DECLARE a ROW(a INT);\n  EXPLAIN SELECT 1 INTO a.a;\nEND;", packet_length=74, is_com_multi=false, 

    is_next_command=false)

    at /home/bar/maria-git/server.10.2-ext/sql/sql_parse.cc:1814

SET sql_mode=ORACLE;

DELIMITER $$

DECLARE

  a ROW(a INT);

BEGIN

  EXPLAIN SELECT 1 INTO a.a;

END;

$$

DELIMITER ;