When you've been trying to figure out one small problem for 2 days.

Yeah? What's the problem?

Yeah, I feel you. “Come on, man, all I want to do is be able to validate this form so the user sees error messages on blur if they typed an unacceptable value in the field and for them not to be able to progress unless all the required fields are valid. Why does this have to be so spaghetti? Is it because I have a parent component and two child functional components? Why am I such an idiot?”

So many times I have found the issue to be a scoping issue.

I was watching a guy at Starbucks once look as frustrated as the rest of us do sometimes and I felt obliged to help him. He couldn't figure out why this.foobar was empty. He was referring to this.foobar in a callback. I was there to point it out to him. He had spent days. I felt much helpful.