Irregularity in proceeding but landlord has lawful right to possession

Where the landlord, at the time of applying for the warrant afore-said, had lawful right to the possession of the premises, or of the part thereof so held over as aforesaid, neither he nor his agent, nor any other person acting in his behalf, shall be deemed to be a trespasser by reason merely of any irregularity or informality in the mode of proceeding for obtaining possession under the authority of this Act but the party aggrieved, if he thinks fit, may bring an action for the irregularity or informality, in which the damage alleged to be sustained thereby shall be specially laid, and may recover full satisfaction for that special damage, with costs of suit, Provided that, if the special damage so laid is not proved, the defendant shall be entitled to judgment, and if proved but assessed by the court at any sum not exceeding two dollars, the plaintiff shall recover no more costs than damages, unless the court or judge before whom the trial has been held certifies upon the record that full cost ought to be allowed.