But this time the machine has made the opposite mistake, detecting a virus that is not there in routine swabs taken from people who have come in with other problems – an overdose, a heart attack, a urine infection – and this doesn’t sound like such a bad thing on the surface; perhaps it’ll be nice to be able to say, ‘You know, we thought you had the virus, but you don’t.’ [...] I am outraged that this error has happened. On top of all the other vile facets of this dismal pandemic – its effects on young and old, its disgusting, disproportionate grip on those who are already disadvantaged – this feels like a twist too far. I am incandescent.
I don't think the bolded incandescent is saying the author is literally glowing white. But then what does it mean?