ยง 2001. Mistakes, omissions, defects and irregularities. At any stage of an action, including the filing of a summons with notice, summons and complaint or petition to commence an action, the court may permit a mistake, omission, defect or irregularity, including the failure to purchase or acquire an index number or other mistake in the filing process, to be corrected, upon such terms as may be just, or, if a substantial right of a party is not prejudiced, the mistake, omission, defect or irregularity shall be disregarded, provided that any applicable fees shall be paid.