property ReadOptions.fieldsPerRecord
Enabling checking number of expected fields for each row.
If positive, each record is required to have the given number of fields. If === 0, it will be set to the number of fields in the first row, so that future rows must have the same field count. If negative, no check is made and records may have a variable number of fields.
If the wrong number of fields is in a row, a ParseError is thrown.