Invalid rrule string generated for single-digit year dtstart dates (ex: "0002-01-01")

[jamesfulford]

Reporting an issue

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• Verify that you've looked through existing issues for duplicates before
  creating a new one
• Code sample reproducing the issue. Be sure to include all input values you
  are using such as the exact RRule string and dates.
• Expected output
• Actual output
• The version of rrule you are using
• Your operating system
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  of the machine showing the bug)

Code reproduction:

const rrule = require('rrule');
console.log(rrule.rrulestr(new rrule.RRule({ dtstart: new Date("0010-01-01T00:00:00Z") }).toString()));

Expected: any RRule object
Actual: error is thrown:

Uncaught Error: Invalid UNTIL value: 00,20101T000000Z
    at untilStringToDate (/Users/jamesfulford/solomon-app/node_modules/rrule/dist/es5/rrule.js:370:15)
    at parseDtstart (/Users/jamesfulford/solomon-app/node_modules/rrule/dist/es5/rrule.js:2165:23)
    at parseInput (/Users/jamesfulford/solomon-app/node_modules/rrule/dist/es5/rrule.js:3429:25)
    at buildRule (/Users/jamesfulford/solomon-app/node_modules/rrule/dist/es5/rrule.js:3477:14)
    at Module.rrulestr (/Users/jamesfulford/solomon-app/node_modules/rrule/dist/es5/rrule.js:3512:12)

It seems that for single-digit year dtstart dates, rrule throws exceptions.

This matters because my app displays a preview of dates while the user is editing the dtstart, and "0002-01-01" is common when the user selects the year and starts typing in the year field (using the build-in <input type="date" /> selector). (Funnily enough, this was a user-discovered bug!) I'm able to fix it in my app by handling when the rrule string generated is invalid, but the library should be producing a valid rrule string in this scenario.

Operating system: MacOS Ventura 13.6.3
Node version: v18.19.0
rrule package version: 2.8.1

Timezone:

$ date
Wed Apr  3 11:38:30 MDT 2024