Can a monk abort a Flurry of Blows after the first bonus-action attack to avoid wasting a ki point (e.g. if the enemy goes down after the first attack)? Or do you have to "declare" Flurry of Blows and therefore spend the ki point before starting your bonus action?
Scenario: After the monk takes the Attack action, they use Flurry of Blows. The first attack drops the target and there's nothing else in range. This is effectively the same as a "normal" bonus-action attack, so do you still burn the ki point? Or is this a situation where the ki ability/Flurry is effectively declared when the second bonus-action attack is used?
From a straight read, I would say that you burn the ki point and the second attack is simply wasted, but that doesn't completely fit with the overall flavor of how 5e has modified their combat rules.