Segfault or assertion upon MyISAM repair

CREATE TABLE t1 (b VARCHAR(1024), c CHAR(3), UNIQUE(b,c)) ENGINE=MyISAM;

INSERT INTO t1 VALUES ('foo','baz');

ALTER TABLE t1 DISABLE KEYS;

SET SESSION myisam_repair_threads= 2;

--error ER_WRONG_VALUE_COUNT_ON_ROW

INSERT INTO t1 SELECT 'qux';

# Cleanup

DROP TABLE t1;

mysqld: /data/src/10.4/sql/field.cc:7281: virtual String* Field_string::val_str(String*, String*): Assertion `!table || table->in_use == _current_thd()' failed.

200726  1:38:58 [ERROR] mysqld got signal 6 ;

#7  0x00007fc5675fcf12 in __GI___assert_fail (assertion=0x55957eaf4b68 "!table || table->in_use == _current_thd()", file=0x55957eaf458b "/data/src/10.4/sql/field.cc", line=7281, function=0x55957eaf92c0 <Field_string::val_str(String*, String*)::__PRETTY_FUNCTION__> "virtual String* Field_string::val_str(String*, String*)") at assert.c:101

#8  0x000055957df8ddda in Field_string::val_str (this=0x7fc550133d38, val_buffer=0x7fc55000bda0, val_ptr=0x7fc55000bda0) at /data/src/10.4/sql/field.cc:7281

#9  0x000055957dfda0f2 in Item_field::val_str (this=0x7fc55000bd70, str=0x7fc55000bda0) at /data/src/10.4/sql/item.cc:3191

#10 0x000055957dcf40d4 in Item::val_str (this=0x7fc55000bd70) at /data/src/10.4/sql/item.h:904

#11 0x000055957e042ba3 in Item_func_hash::val_int (this=0x7fc55012c748) at /data/src/10.4/sql/item_func.cc:1745

#12 0x000055957dfe4458 in Item::save_int_in_field (this=0x7fc55012c748, field=0x7fc550133e20, no_conversions=false) at /data/src/10.4/sql/item.cc:6582

#13 0x000055957de794da in Type_handler_int_result::Item_save_in_field (this=0x55957f42aba8 <type_handler_long>, item=0x7fc55012c748, field=0x7fc550133e20, no_conversions=false) at /data/src/10.4/sql/sql_type.cc:3672

#14 0x000055957dfe4503 in Item::save_in_field (this=0x7fc55012c748, field=0x7fc550133e20, no_conversions=false) at /data/src/10.4/sql/item.cc:6592

#15 0x000055957dd96ce4 in TABLE::update_virtual_field (this=0x7fc5501822c0, vf=0x7fc550133e20) at /data/src/10.4/sql/table.cc:8393

#16 0x000055957e7330d6 in compute_vcols (info=0x7fc55012d830, record=0x7fc550071350 "\370\003", keynum=0) at /data/src/10.4/storage/myisam/ha_myisam.cc:707

#17 0x000055957e74754b in sort_get_next_record (sort_param=0x7fc550070b80) at /data/src/10.4/storage/myisam/mi_check.c:3666

#18 0x000055957e745754 in sort_key_read (sort_param=0x7fc550070b80, key=0x7fc544000b08) at /data/src/10.4/storage/myisam/mi_check.c:3130

#19 0x000055957e78fb9d in thr_find_all_keys_exec (sort_param=0x7fc550070b80) at /data/src/10.4/storage/myisam/sort.c:448

#20 0x000055957e78fd3a in thr_find_all_keys (arg=0x7fc550070b80) at /data/src/10.4/storage/myisam/sort.c:507

#21 0x000055957e7dd879 in pfs_spawn_thread (arg=0x7fc550072f30) at /data/src/10.4/storage/perfschema/pfs.cc:1869

#22 0x00007fc5695854a4 in start_thread (arg=0x7fc56175c700) at pthread_create.c:456

#23 0x00007fc5676b9d0f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97