It seems my previous question was misunderstood. A user suggested that I ask a new question instead of rewording the previous one.
The answers to that question addressed whether a decision that a case is moot can be appealed. My question is whether a judgment can be appealed on the grounds that it was moot.
For example, in a Judgement of Possession (JOP) action, suppose a tenant vacates the premises & returs the keys to the landlord prior to the trial. The court enters a judgement for possession (JOP) - despite evidence showing that the landlord repossessed the premises. The tenant now wants to appeal the JOP on grounds that it was moot (as he already vacated the premises prior to the JOP).
In this question a user suggests that the court may not have jurisdiction to enter a judgement in such cases:
It seems like the action for possession would be moot under these circumstances, prohibiting the court from entering judgment.
If the court lacks jurisdiction then the JOP should be appealable. However, if mootness is merely a "discretionary doctrine" reflecting a desire to preserve an adversarial context and a concern for judicial economy then once the judgement has been entered these concerns are no longer valid and the judgement should not be appealable.
Which approach is the correct one?
Update:
As to the question "why does it matter" @user253751 is correct:
The tenant doesn't want a JOP on their record when they actually followed the contract and moved out prior to the trial
