How do I report a Google Search bug?

from blog The Desolation of Blog, | ↗ original
I found a Google Search bug in Safari on iOS. Or rather, a StopTheMadness customer found the bug and reported it to me. I investigated and determined, to my relief, that the bug wasn't mine, because I could (eventually) reproduce it with StopTheMadness disabled. The question is, how do I report this bug to Google? They have a public issue...