Generally, a cause, issue, or appeal is moot when the court's action on the merits cannot have any practical legal effect on the rights of the parties. See State v. Nayeb, No. 05-15-00279-CR, 2016 WL 165686, at *4 (Tex. App.-Dallas Jan. 13, 2016, no pet.) (mem. op., not designated for publication) (citing Smith v. State, 848 S.W.2d 891, 893 (Tex. App.-Houston [14th Dist.] 1993, pet. ref'd)). Any opinion by an appellate court ruling on a moot issue would be purely advisory, and Texas courts have no jurisdiction to issue advisory opinions.