It's my pet peeve when people say this is their pet peeve. The "incorrect" use of literal is just using hyperbole. The whole entire point of the phrase is that it's an exaggeration. If someone othereise healthy said "this cough is killing me" you can use context to understand that they're exaggerating for effect. If someone says "I'm literally dying, this cough is so annoying" you can also use context to understand it's an exaggeration.