DDL fails to drop and re-create FTS index

USE test;

CREATE TABLE t (FTS_DOC_ID BIGINT UNSIGNED PRIMARY KEY,c2 VARCHAR(200),FULLTEXT(c2));

ALTER TABLE t PACK_KEYS=0;

Core was generated by `/test/MD030620-mariadb-10.5.4-linux-x86_64-opt/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:57

[Current thread is 1 (Thread 0x14c7cb892700 (LWP 1761235))]

(gdb) bt

(gdb) (gdb) #0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11) at ../sysdeps/unix/sysv/linux/pthread_kill.c:57

#1  0x0000564309c9f647 in my_write_core (sig=sig@entry=11) at /test/10.5_opt/mysys/stacktrace.c:518

#2  0x0000564309661f4a in handle_fatal_signal (sig=11) at /test/10.5_opt/sql/signal_handler.cc:330

#3  <signal handler called>

#4  fts_add_index (index=0x14c7aac35a80, table=0x14c7aac9a300) at /test/10.5_opt/storage/innobase/fts/fts0fts.cc:671

#5  0x000056430999fb47 in ha_innobase::commit_inplace_alter_table (this=<optimized out>, altered_table=<optimized out>, ha_alter_info=<optimized out>, commit=<optimized out>) at /test/10.5_opt/storage/innobase/handler/handler0alter.cc:11187

#6  0x0000564309504f5b in mysql_inplace_alter_table (target_mdl_request=0x14c7cb88e4f0, alter_ctx=0x14c7cb88fa20, inplace_supported=<optimized out>, ha_alter_info=0x14c7cb88d690, altered_table=0x14c7cb88d730, table=<optimized out>, table_list=0x14c7aac47110, thd=0x14c7aac12018) at /test/10.5_opt/sql/sql_table.cc:7936

#7  mysql_alter_table (thd=thd@entry=0x14c7aac12018, new_db=new_db@entry=0x14c7aac16718, new_name=new_name@entry=0x14c7aac16b20, create_info=create_info@entry=0x14c7cb890600, table_list=<optimized out>, table_list@entry=0x14c7aac47110, alter_info=alter_info@entry=0x14c7cb890530, order_num=0, order=0x0, ignore=false, if_exists=false) at /test/10.5_opt/sql/sql_table.cc:10457

#8  0x0000564309560371 in Sql_cmd_alter_table::execute (this=<optimized out>, thd=0x14c7aac12018) at /test/10.5_opt/sql/sql_alter.cc:532

#9  0x000056430946c45f in mysql_execute_command (thd=thd@entry=0x14c7aac12018) at /test/10.5_opt/sql/sql_parse.cc:5950

#10 0x0000564309472f1c in mysql_parse (thd=0x14c7aac12018, rawbuf=<optimized out>, length=25, parser_state=0x14c7cb8914b0, is_com_multi=<optimized out>, is_next_command=<optimized out>) at /test/10.5_opt/sql/sql_parse.cc:7992

#11 0x0000564309468235 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x14c7aac12018, packet=packet@entry=0x14c7aac3a019 "ALTER TABLE t PACK_KEYS=0", packet_length=packet_length@entry=25, is_com_multi=is_com_multi@entry=false, is_next_command=is_next_command@entry=false) at /test/10.5_opt/sql/sql_parse.cc:1874

#12 0x0000564309466644 in do_command (thd=0x14c7aac12018) at /test/10.5_opt/sql/sql_parse.cc:1355

#13 0x000056430955b7c1 in do_handle_one_connection (connect=<optimized out>, connect@entry=0x14c7cb0329b8, put_in_cache=put_in_cache@entry=true) at /test/10.5_opt/sql/sql_connect.cc:1411

#14 0x000056430955bb24 in handle_one_connection (arg=arg@entry=0x14c7cb0329b8) at /test/10.5_opt/sql/sql_connect.cc:1313

#15 0x00005643098c817a in pfs_spawn_thread (arg=0x14c7cb04b018) at /test/10.5_opt/storage/perfschema/pfs.cc:2201

#16 0x000014c7cc8896db in start_thread (arg=0x14c7cb892700) at pthread_create.c:463

#17 0x000014c7cbc8788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95