It's been happening throughout history, of course. Beautiful accidents. Unintentional intentions. We can't plan these mistakes, but wish we could. What seems like disaster, turns into the spark that ignites what we perceive later as "rightly so".
And it happens all the time when I'm designing. Oops, I dumped a white paint can where color used to be. Wait. That's nice. It's become a part of my process. A part I can't anticipate, or account for, but a part nonetheless.
The serendipitous nature of design is part of what makes it so rewarding—those eureka moments.