system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Boggarts. What if your biggest fear was was something without a shape?

Like being afraid of being alone, of heights, a failing economy or like what Ron said to Hermione; "Scoring only 9 out of 10"

Would it keep going down your list of fears until it finds the first thing that makes you uncomfortable, that IS tangible?
gpt
It'd probably try and find a manifestation of that.  Lupin wasn't scared of the moon per se, but of the fact that he'd turn into a werewolf.  But it couldn't contextualize that fear, so it showed him the moon.

Keep in mind, though, that the Boggarts aren't terribly intelligent. They're creatures but not all knowing or all powerful, just magical.  They're limited in what they can do or show, they just do their best.  They can be defeated with a simple spell and some laughter by schoolchildren.