If several issues are presented by the pleadings and, on the trial of one or more of such issues, an error or ground for a new trial intervenes which does not affect the legality of the trial or disposition of the other issue or issues, judgment shall not be arrested or reversed, nor a new trial granted, except so far as relates to the particular issue or issues in the trial of which such error or ground for a new trial intervened.

(1949 Rev., S. 8007.)