On the portfolio, the light/dark toggle uses View Transitions when the browser exposes them. An impatient user double-clicks → the transition aborts → AbortError.
I had let it surface as a real exception. Sentry loved that. I did not.
Mental fix
try {
await document.startViewTransition(() => applyTheme(next)).finished;
} catch (err) {
if (err?.name === 'AbortError') return;
throw err;
}
Lesson
A useful REX documents the symptom, the cause, and the guardrail. Not a novel. This one cost me an hour — and saved me from “just disable View Transitions” panic.