Server crashes in String::ptr / Item_func_json_depth::val_int

SELECT JSON_DEPTH(CAST(NULL as JSON));

#3  <signal handler called>

#4  0x00007f815df81806 in String::ptr (this=0x0) at /data/src/10.2/sql/sql_string.h:211

#5  0x00007f815e488a9e in Item_func_json_depth::val_int (this=0x7f81168602e0) at /data/src/10.2/sql/item_jsonfunc.cc:1229

#6  0x00007f815e2d568d in Item::send (this=0x7f81168602e0, protocol=0x7f8116816600, buffer=0x7f815f1487a0) at /data/src/10.2/sql/item.cc:6775

#7  0x00007f815df84178 in Protocol::send_result_set_row (this=0x7f8116816600, row_items=0x7f811681a3a8) at /data/src/10.2/sql/protocol.cc:979

#8  0x00007f815e002e50 in select_send::send_data (this=0x7f8116860480, items=...) at /data/src/10.2/sql/sql_class.cc:2915

#9  0x00007f815e08fe4f in JOIN::exec_inner (this=0x7f81168604a0) at /data/src/10.2/sql/sql_select.cc:3278

#10 0x00007f815e08f8ea in JOIN::exec (this=0x7f81168604a0) at /data/src/10.2/sql/sql_select.cc:3198

#11 0x00007f815e090a41 in mysql_select (thd=0x7f8116816070, tables=0x0, wild_num=0, fields=..., conds=0x0, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7f8116860480, unit=0x7f8116819b48, select_lex=0x7f811681a280) at /data/src/10.2/sql/sql_select.cc:3583

#12 0x00007f815e085b25 in handle_select (thd=0x7f8116816070, lex=0x7f8116819a80, result=0x7f8116860480, setup_tables_done_option=0) at /data/src/10.2/sql/sql_select.cc:373

#13 0x00007f815e05246f in execute_sqlcom_select (thd=0x7f8116816070, all_tables=0x0) at /data/src/10.2/sql/sql_parse.cc:6356

#14 0x00007f815e047f2a in mysql_execute_command (thd=0x7f8116816070) at /data/src/10.2/sql/sql_parse.cc:3379

#15 0x00007f815e055e2e in mysql_parse (thd=0x7f8116816070, rawbuf=0x7f8116860088 "SELECT JSON_DEPTH(CAST(NULL as JSON))", length=37, parser_state=0x7f815f149e20, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:7799

#16 0x00007f815e043b7e in dispatch_command (command=COM_QUERY, thd=0x7f8116816070, packet=0x7f8116854071 "", packet_length=37, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:1808

#17 0x00007f815e042558 in do_command (thd=0x7f8116816070) at /data/src/10.2/sql/sql_parse.cc:1368

#18 0x00007f815e189a26 in do_handle_one_connection (connect=0x7f815ac5ff70) at /data/src/10.2/sql/sql_connect.cc:1354

#19 0x00007f815e1897b3 in handle_one_connection (arg=0x7f815ac5ff70) at /data/src/10.2/sql/sql_connect.cc:1260

#20 0x00007f815d6810a4 in start_thread (arg=0x7f815f14b300) at pthread_create.c:309

#21 0x00007f815b62e87d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111