SHOW CREATE for nonexistent procedure triggers segfault when cache_sp_in_show_create is enabled

set debug_dbug="+d,cache_sp_in_show_create";

show create procedure non_existent_procedure;

Core was generated by `/src/MariaDB-server.git/sql/mariadbd --defaults-group-suffix=.1 --defaults-file=/src/MariaDB-server.git/mysql-test/var/my.cnf --log-output=file --default-storage-engine=MyISAM --core-file --loose-debug-sync-timeout=300'.

Program terminated with signal SIGSEGV, Segmentation fault.

Thread 1 (Thread 0x7fa7e354c6c0 (LWP 462759)):

#0  __pthread_kill_implementation (threadid=<optimized out>, signo=11, no_tid=0) at ./nptl/pthread_kill.c:44

#1  __pthread_kill_internal (threadid=<optimized out>, signo=11) at ./nptl/pthread_kill.c:89

#2  __GI___pthread_kill (threadid=<optimized out>, signo=11) at ./nptl/pthread_kill.c:100

#3  0x00005b0454a03f71 in my_write_core (sig=11) at /src/MariaDB-server.git/mysys/stacktrace.c:424

#4  0x00005b0454012d4e in handle_fatal_signal (sig=11) at /src/MariaDB-server.git/sql/signal_handler.cc:298

#5  <signal handler called>

#6  0x00005b0453a76ab7 in check_show_routine_access (thd=0x7fa7cc000dc8, sp=0x0, full_access=0x7fa7e354a8f6) at /src/MariaDB-server.git/sql/sp_head.cc:2978

#7  0x00005b0453a772ce in sp_head::show_create_routine (this=0x0, thd=0x7fa7cc000dc8, sph=0x5b04557ddc60 <sp_handler_procedure>) at /src/MariaDB-server.git/sql/sp_head.cc:3093

#8  0x00005b0454225a6a in Sp_handler::sp_show_create_routine (this=0x5b04557ddc60 <sp_handler_procedure>, thd=0x7fa7cc000dc8, name=0x7fa7cc0182a0) at /src/MariaDB-server.git/sql/sp.cc:2016

#9  0x00005b0453baadb9 in mysql_execute_command (thd=0x7fa7cc000dc8, is_called_from_prepared_stmt=false) at /src/MariaDB-server.git/sql/sql_parse.cc:5621

#10 0x00005b0453bb215c in mysql_parse (thd=0x7fa7cc000dc8, rawbuf=0x7fa7cc0181f0 "show create procedure p3", length=24, parser_state=0x7fa7e354b2c0) at /src/MariaDB-server.git/sql/sql_parse.cc:7891

#11 0x00005b0453b9d967 in dispatch_command (command=COM_QUERY, thd=0x7fa7cc000dc8, packet=0x7fa7cc00c149 "show create procedure p3", packet_length=24, blocking=true) at /src/MariaDB-server.git/sql/sql_parse.cc:1877

#12 0x00005b0453b9c24c in do_command (thd=0x7fa7cc000dc8, blocking=true) at /src/MariaDB-server.git/sql/sql_parse.cc:1416

#13 0x00005b0453db7a6a in do_handle_one_connection (connect=0x5b045bffa0f8, put_in_cache=true) at /src/MariaDB-server.git/sql/sql_connect.cc:1414

#14 0x00005b0453db77df in handle_one_connection (arg=0x5b045bc747c8) at /src/MariaDB-server.git/sql/sql_connect.cc:1326

#15 0x00005b045439844e in pfs_spawn_thread (arg=0x5b045c014e38) at /src/MariaDB-server.git/storage/perfschema/pfs.cc:2198

#16 0x00007fa7f26a2ef1 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:448

#17 0x00007fa7f273445c in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78