Suppose I want to add a qualifier to a noun that isn't necessary for understanding, so I decide to put it in parentheses. If the adjective in parentheses would change whether I use "a" or "an" as an article, which one is correct?

For example, as in the title, I want to mention that a problem is obvious. Without the qualifier it would be "a problem", with it "an obvious problem". Would it be "an (obvious) problem" or "a (obvious) problem"?

I suspect the first one to be correct, but is that true? My understanding of parentheses is that the sentence should make sense with or without the part between them, but in this case one option sounds weird when including it and one sounds strange when leaving it out.

Edit: Please note that this is not a duplicate of a / an - adjective - noun . There, the question is about an adjective directly following the article without any parentheses. I'm asking whether the special case with parentheses changes anything. Also, this is basically a nitpicking question: I know how to rephrase the expression to avoid the issue, but I want to know what is correct.