Invalid CREATE INDEX fails to report error correctly

The following test is crashing the MariaDB Server 10.2 debug build in the CREATE INDEX:

--source include/have_innodb.inc

SET GLOBAL innodb_file_format=Barracuda;

SET GLOBAL innodb_large_prefix=0;

CREATE TABLE t (a VARCHAR(4000)) ROW_FORMAT=DYNAMIC ENGINE=InnoDB;

--error ER_TOO_LONG_KEY

CREATE INDEX prefix_idx ON t(a(1000));

DROP TABLE t;

The innodb_file_format and ROW_FORMAT=DYNAMIC are defaults. I added them only to test this in 10.0 and 10.1, which rightfully reported the following:

mysqltest: At line 7: query 'CREATE INDEX prefix_idx ON t(a(1000))' succeeded - should have failed with errno 1071...

In 10.2 we instead get the famous debug assertion failure:

mysqld: /mariadb/10.2/sql/sql_error.cc:380: void Diagnostics_area::set_ok_status(ulonglong, ulonglong, const char *): Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed.