The table securepoll_lists does not have a primary key or a unique index.
Please add a primary key as best practice by choosing one or more relevant columns which must be unique by functional, tables.json contains a fixme which suggest splists_name to become unique
Current schema
CREATE TABLE /*_*/securepoll_lists ( li_name VARBINARY(255) DEFAULT NULL, li_member INT NOT NULL, INDEX splists_name (li_name, li_member), INDEX splists_member (li_member, li_name) ) /*$wgDBTableOptions*/;
Primary key helps on database maintenance and it can make deletions on the table easier and avoid deadlocks with other deletion or inserts