The beast has a name - "Serendipity"
There are numerous definitions for Serendipity: the faculty of making desirable but unsought-for discoveries (Macquarie Dictionary) the occurrence and development of events by chance in a happy or beneficial way. "a fortunate stroke of serendipity" (Oxford Dictionary) the fact of finding interesting or valuable things by chance (Cambridge Dictionary) the luck some people have in finding or creating interesting or valuable things by chance (Collins Dictionary) the faculty or phenomenon of finding valuable or agreeable things not sought for (Merriam-Webster) an aptitude for making desirable discoveries by accident, good fortune, good luck (Dictionary.com) a happy accident or an unplanned fortunate discovery (Wikipedia), and hundreds more variations. The favoured variation for us: "finding something nice while looking for something else".