CodePen example: https://codepen.io/pomah33/pen/MWrRKMb?editors=0010
If an error was thrown in Deferred callback, this error doesn't appear in console, which makes debugging more difficult
Error possibly was caused by this PR: 6d97370#diff-24d8a479ae56566c65690364aa2156fff7613fd38bd024153579f15d92b26f91L73, when deferred-like method .done was changed to promise-like .then
But on error in 'then' section of deferred (not promise) hides without appearing in console
Samples to try in dev console:
new Promise((resolve) => { window.r1 = resolve; }).then(() => { throw new Error('my error'); })
r1()
const d = new $.Deferred()
d.then(() => { throw new Error('my error'); })
d.resolve()