Assertion `ds_control' failed in st_debug_sync_action* debug_sync_get_action(THD*, const char*, uint)

SET GLOBAL debug_dbug='d,sync.alter_opened_table';

CREATE TABLE t (a TEXT,FULLTEXT KEY(a));

ALTER TABLE t ADD c TIMESTAMP;

mysqld: /test/10.6_dbg/sql/debug_sync.cc:661: st_debug_sync_action* debug_sync_get_action(THD*, const char*, uint): Assertion `ds_control' failed.

Core was generated by `/test/MD160321-mariadb-10.6.0-linux-x86_64-dbg/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGABRT, Aborted.

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=6)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

[Current thread is 1 (Thread 0x14bea9bb3700 (LWP 3928514))]

(gdb) bt

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

#1  0x000055e7a059cd0b in my_write_core (sig=sig@entry=6) at /test/10.6_dbg/mysys/stacktrace.c:424

#2  0x000055e79fd34313 in handle_fatal_signal (sig=6) at /test/10.6_dbg/sql/signal_handler.cc:331

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#5  0x000014becca47859 in __GI_abort () at abort.c:79

#6  0x000014becca47729 in __assert_fail_base (fmt=0x14beccbdd588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x55e7a0715bd4 "ds_control", file=0x55e7a0715f38 "/test/10.6_dbg/sql/debug_sync.cc", line=661, function=<optimized out>) at assert.c:92

#7  0x000014becca58f36 in __GI___assert_fail (assertion=assertion@entry=0x55e7a0715bd4 "ds_control", file=file@entry=0x55e7a0715f38 "/test/10.6_dbg/sql/debug_sync.cc", line=line@entry=661, function=function@entry=0x55e7a0716518 "st_debug_sync_action* debug_sync_get_action(THD*, const char*, uint)") at assert.c:101

#8  0x000055e79fa9696e in debug_sync_get_action (name_len=3, dsp_name=0x14be7c014748 "now", thd=0x14be7c000db8) at /test/10.6_dbg/sql/debug_sync.cc:661

#9  debug_sync_eval_action (thd=thd@entry=0x14be7c000db8, action_str=<optimized out>, action_end=0x14be7c01476e "") at /test/10.6_dbg/sql/debug_sync.cc:1030

#10 0x000055e79fa98670 in debug_sync_set_action (thd=thd@entry=0x14be7c000db8, action_str=action_str@entry=0x14bea9bb0920 "now wait_for signal.alter_opened_table", len=len@entry=38) at /test/10.6_dbg/sql/debug_sync.cc:1623

#11 0x000055e79fb4cb74 in mysql_alter_table (thd=thd@entry=0x14be7c000db8, new_db=new_db@entry=0x14be7c005838, new_name=new_name@entry=0x14be7c005c58, create_info=create_info@entry=0x14bea9bb1550, table_list=<optimized out>, table_list@entry=0x14be7c013c80, alter_info=alter_info@entry=0x14bea9bb1460, order_num=0, order=0x0, ignore=false, if_exists=false) at /test/10.6_dbg/sql/sql_table.cc:10131

#12 0x000055e79fbd4e05 in Sql_cmd_alter_table::execute (this=<optimized out>, thd=0x14be7c000db8) at /test/10.6_dbg/sql/structs.h:563

#13 0x000055e79fa7c87b in mysql_execute_command (thd=thd@entry=0x14be7c000db8) at /test/10.6_dbg/sql/sql_parse.cc:5972

#14 0x000055e79fa63876 in mysql_parse (thd=thd@entry=0x14be7c000db8, rawbuf=<optimized out>, length=<optimized out>, parser_state=parser_state@entry=0x14bea9bb2410) at /test/10.6_dbg/sql/sql_parse.cc:7998

#15 0x000055e79fa721e7 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x14be7c000db8, packet=packet@entry=0x14be7c00b359 "ALTER TABLE t ADD c TIMESTAMP", packet_length=packet_length@entry=29, blocking=blocking@entry=true) at /test/10.6_dbg/sql/sql_class.h:1318

#16 0x000055e79fa755c1 in do_command (thd=0x14be7c000db8, blocking=blocking@entry=true) at /test/10.6_dbg/sql/sql_parse.cc:1397

#17 0x000055e79fbcd178 in do_handle_one_connection (connect=<optimized out>, connect@entry=0x55e7a294e618, put_in_cache=put_in_cache@entry=true) at /test/10.6_dbg/sql/sql_connect.cc:1410

#18 0x000055e79fbcd77d in handle_one_connection (arg=arg@entry=0x55e7a294e618) at /test/10.6_dbg/sql/sql_connect.cc:1312

#19 0x000055e7a0078a5b in pfs_spawn_thread (arg=0x55e7a2872d98) at /test/10.6_dbg/storage/perfschema/pfs.cc:2201

#20 0x000014beccf55609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#21 0x000014beccb44293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95