SIGSEGV's in GetDefaultPrec and JSON::GetType on SELECT after loading ha_connect.so, and UBSAN: member call on null pointer in JVALUE::GetValType()

CREATE FUNCTION json_array_add RETURNS STRING SONAME 'ha_connect.so';

SELECT json_array_add('[5,3,8,7,9]' a,4,9);

Core was generated by `/test/MD170524-mariadb-11.5.0-linux-x86_64-dbg/bin/mariadbd --no-defaults --max'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  0x0000000000000000 in ?? ()

[Current thread is 1 (LWP 1374315)]

(gdb) bt

#0  0x0000000000000000 in ?? ()

#1  0x0000145c8c43378b in GetDefaultPrec ()at /test/11.5_dbg/storage/connect/ha_connect.cc:507

#2  0x0000145c8c45bbd5 in Serialize (g=g@entry=0x145c60036350, jsp=jsp@entry=0x145c600388a8, fn=fn@entry=0x0, pretty=pretty@entry=0)at /test/11.5_dbg/storage/connect/json.cpp:269

#3  0x0000145c8c4620b9 in MakeResult (g=g@entry=0x145c60036350, args=args@entry=0x145c6001b6c8, top=0x145c600388a8, n=3)at /test/11.5_dbg/storage/connect/jsonudf.cpp:1450

#4  0x0000145c8c463bf9 in json_array_add (initid=<optimized out>, args=0x145c6001b6c8, result=<optimized out>, res_length=0x145c8c5a1d28, is_null=0x145c8c5a1d27 "", error=0x145c6001b738 "")at /test/11.5_dbg/storage/connect/jsonudf.cpp:2302

#5  0x0000563bfff8bcd8 in udf_handler::val_str (this=this@entry=0x145c6001b6b8, str=str@entry=0x145c8c5a1e30, save_str=save_str@entry=0x145c6001b630)at /test/11.5_dbg/sql/sql_string.h:359

#6  0x0000563bfff8be04 in Item_func_udf_str::val_str (this=0x145c6001b608, str=0x145c8c5a1e30) at /test/11.5_dbg/sql/item_func.cc:3838

#7  0x0000563bffe2f84c in Type_handler::Item_send_str (this=<optimized out>, item=0x145c6001b608, protocol=0x145c60001370, buf=<optimized out>)at /test/11.5_dbg/sql/sql_type.cc:7501

#8  0x0000563bffd47899 in Type_handler_string_result::Item_send (this=<optimized out>, item=<optimized out>, protocol=<optimized out>, buf=<optimized out>) at /test/11.5_dbg/sql/sql_type.h:5659

#9  0x0000563bffab6642 in Item::send (this=0x145c6001b608, protocol=0x145c60001370, buffer=0x145c8c5a1e00)at /test/11.5_dbg/sql/item.h:1254

#10 0x0000563bffaed671 in Protocol::send_result_set_row (this=this@entry=0x145c60001370, row_items=row_items@entry=0x145c6001b1c0)at /test/11.5_dbg/sql/protocol.cc:1359

#11 0x0000563bffb6a759 in select_send::send_data (this=0x145c6001c0d8, items=@0x145c6001b1c0: {<base_list> = {<Sql_alloc> = {<No data fields>}, first = 0x145c6001b780, last = 0x145c6001b780, elements = 1}, <No data fields>})at /test/11.5_dbg/sql/sql_class.cc:3189

#12 0x0000563bffc7322e in select_result_sink::send_data_with_check (sent=0, u=<optimized out>, items=<optimized out>, this=<optimized out>)at /test/11.5_dbg/sql/sql_class.h:6090

#13 JOIN::exec_inner (this=this@entry=0x145c6001c100)at /test/11.5_dbg/sql/sql_select.cc:4862

#14 0x0000563bffc7408c in JOIN::exec (this=this@entry=0x145c6001c100)at /test/11.5_dbg/sql/sql_select.cc:4774

#15 0x0000563bffc71e95 in mysql_select (thd=thd@entry=0x145c60000d58, tables=0x0, fields=@0x145c6001b1c0: {<base_list> = {<Sql_alloc> = {<No data fields>}, first = 0x145c6001b780, last = 0x145c6001b780, elements = 1}, <No data fields>}, conds=0x0, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2164525824, result=0x145c6001c0d8, unit=0x145c600051f0, select_lex=0x145c6001af08) at /test/11.5_dbg/sql/sql_select.cc:5304

#16 0x0000563bffc726be in handle_select (thd=thd@entry=0x145c60000d58, lex=lex@entry=0x145c60005110, result=result@entry=0x145c6001c0d8, setup_tables_done_option=setup_tables_done_option@entry=0)at /test/11.5_dbg/sql/sql_select.cc:630

#17 0x0000563bffbd23c7 in execute_sqlcom_select (thd=thd@entry=0x145c60000d58, all_tables=0x0) at /test/11.5_dbg/sql/sql_parse.cc:6093

#18 0x0000563bffbdd720 in mysql_execute_command (thd=thd@entry=0x145c60000d58, is_called_from_prepared_stmt=is_called_from_prepared_stmt@entry=false)at /test/11.5_dbg/sql/sql_parse.cc:3942

#19 0x0000563bffbe40a5 in mysql_parse (thd=thd@entry=0x145c60000d58, rawbuf=<optimized out>, length=<optimized out>, parser_state=parser_state@entry=0x145c8c5a3230)at /test/11.5_dbg/sql/sql_parse.cc:7815

#20 0x0000563bffbe6593 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x145c60000d58, packet=packet@entry=0x145c6000b1e9 "", packet_length=packet_length@entry=42, blocking=blocking@entry=true)at /test/11.5_dbg/sql/sql_class.h:254

#21 0x0000563bffbe8861 in do_command (thd=0x145c60000d58, blocking=blocking@entry=true) at /test/11.5_dbg/sql/sql_parse.cc:1405

#22 0x0000563bffd5d1ce in do_handle_one_connection (connect=<optimized out>, connect@entry=0x563c0358c8a8, put_in_cache=put_in_cache@entry=true)at /test/11.5_dbg/sql/sql_connect.cc:1445

#23 0x0000563bffd5d4ce in handle_one_connection (arg=arg@entry=0x563c0358c8a8)at /test/11.5_dbg/sql/sql_connect.cc:1347

#24 0x0000563c001a1980 in pfs_spawn_thread (arg=0x563c03542638)at /test/11.5_dbg/storage/perfschema/pfs.cc:2201

#25 0x0000145cb0a97ada in start_thread (arg=<optimized out>)at ./nptl/pthread_create.c:444

#26 0x0000145cb0b2847c in clone3 ()at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78