[fix] `next` seems to produce erroneous results esp around the full hour

[chandru89new]

Describe the bug

• Node.js version: 16.5.0
• OS & version: MacOS Mojave

Actual behavior

When using next on a cron expression (eg */13 * * * * -> every 13 minutes), it seems to generate occurrences that are shorter than 13 minutes every once in a while.

Eg:

const later = require('@breejs/later')
const cron = '*/13 * * * *'

const sched = later.parse.cron(cron)
const nexts = later.schedule(sched).next(11, new Date(2022,10,10,05,00))
console.log(nexts)

produces:

[
  2022-11-10T05:00:00.000Z,
  2022-11-10T05:13:00.000Z,
  2022-11-10T05:26:00.000Z,
  2022-11-10T05:39:00.000Z,
  2022-11-10T05:52:00.000Z,
  2022-11-10T06:00:00.000Z,
  2022-11-10T06:13:00.000Z,
  2022-11-10T06:26:00.000Z,
  2022-11-10T06:39:00.000Z,
  2022-11-10T06:52:00.000Z,
  2022-11-10T07:00:00.000Z
]

After 5:52:00, it should be 6:05:00 and after 6:52:00 (which technically should not be a possible time in the schedule), it should be 7:05:00.

Expected behavior

It should compute the right time for the interval.

Code to reproduce

const later = require('@breejs/later')
const cron = '*/13 * * * *'

const sched = later.parse.cron(cron)
const nexts = later.schedule(sched).next(11, new Date(2022,10,10,05,00))
console.log(nexts)

Checklist

• [x] I have read the documentation.
• [x] I have tried my code with the latest version of Node.js and @breejs/later.

[chandru89new]

Sorry about this, but closing this because it's how cron works by design and not a bug of this library.