It was most likely a moth, butterflies are not out at night, and moths are well known to be drawn to flames. Lots of bugs are, it’s why bug zappers work. It’s literally a phrase to indicate an unhealthy obsession “Like a moth drawn to a flame”.
After that, falling on something next to the candle is inevitable. This could all be nothing.
On the other hand, if you intuitively sense this has significance, it’s like interpreting dreams, you have to know what moths mean to you, what it’s death means to you, and what message could be within those meanings.
This usually depends what you were feeling and the intention in your working, which is the most important part (and yet you didn’t mention it?)
Had you just asked for a sign? Were you doing a baneful working? What other connections can you personally make for this, your personal working?