Em dash vs. en dash

I love the plugin so far; however, I’m finding an issue with its em dash checker. Under the “Your style guide” tab, a checkbox reads, “Long em-dash for parenthetical asides.” When enabled, the plugin is able to flag hyphens that are improperly employed as dashes, but it does so with the warning, “Use – dash,” and what it prints here instead of the lovely, eternally elegant em dash (“—”) is actually that nefarious pretender among punctuation, that ugly cousin: the en dash (“–”).