Exception in production

gistfile1.txt

ActiveRecord::StatementInvalid (PG::SyntaxError: ERROR:  syntax error at or near ")"
LINE 20: ...(CASE WHEN lower(partners_languages.language) IN () THEN 1 E...
                                                              ^
:
        SELECT users.id FROM (
          SELECT users.id, (CASE WHEN lower(users.my_sector) = lower('Real Estate') THEN users.score + 2 ELSE users.score END) AS score
          FROM (
            SELECT users.id, users.my_sector, SUM(location) AS score
            FROM (
              SELECT
                users.id,
                users.my_sector,
                (CASE WHEN lower(partners_locations.location) LIKE '%%' THEN users.score + 1 ELSE score END) AS location
              FROM (
                SELECT
                  users.id,
                  users.my_sector,
                  SUM(language) AS score
                FROM (
                  SELECT
                    users.id,
                    users.my_sector,
                    (CASE WHEN lower(partners_languages.language) IN () THEN 1 ELSE 0 END) AS language
                  FROM users
                  LEFT JOIN partners_languages ON users.id = partners_languages.user_id
                  WHERE users.profile_image_file_name IS NOT NULL
                ) AS users
                GROUP BY users.id, users.my_sector
              ) AS users
              LEFT JOIN partners_locations ON users.id = partners_locations.user_id
            ) AS users
            GROUP BY users.id, users.my_sector
          ) AS users
        ) AS users
        WHERE users.score > 1
        ORDER BY users.score DESC
      ):
  app/models/user.rb:69:in `recommended_users'
  app/controllers/application_controller.rb:76:in `set_recommended_users'