Why is it ironic that Pyramus and Thisbe is a lamentable comedy?

In ActI sc.2. Quince declares that they are going to stage: "The most lamentable comedy, and/ most cruel death of Pyramus and Thisby."

Situational Irony: 'Lamentable comedy' is an oxymoron and clearly underscores the incongruity of the choice of a tragedy to be staged during the wedding celebrations of Theseus and Hippolyta.

Verbal Irony: results when Bottom suggests that he play both the roles of Pyramus and Thisby simultaneously:"let me play Thisby too I'll/ speak in a monstrous little voice. 'Thisne,/ Thisne; Ah pyramus lover dear! thy Thisby dear, and lover dear." Act I Sc.2. The humour results not just because Bottom is ready to play both the roles but also because of the nasal twang when he pronounces 'Thisby' as 'Thisne'.

Dramatic Irony: The intertext from Ovid's "Metamorphoses" would have been familiar to a Shkespearean audience. They would have enjoyed Shakespeare's hilarious parody, even as they would have  straightaway recognized the parallels between the Pyramus Thisby story and the stories of the lovers of the main play.