Luxon DateTime is not assignable to type ICalDateTimeValue in Typescript

[ismarslomic]

When I'm trying to assign an Luxon DateTime to the start and end properties of the ICalEvent (Typescript) I get following error message in IntelliJ and tsc:

index.ts:9:5 - error TS2322: Type 'DateTime' is not assignable to type '{ (): ICalDateTimeValue | null; (start: ICalDateTimeValue): ICalEvent; } | ICalDateTimeValue | null | undefined'.
  Type 'DateTime' is not assignable to type 'ICalLuxonDateTimeStub'.
    The types returned by 'toJSON()' are incompatible between these types.
      Type 'string | null' is not assignable to type 'string'.
        Type 'null' is not assignable to type 'string'.

9     start: startTime,
      ~~~~~

  node_modules/ical-generator/dist/index.d.cts:951:5
    951     start(): ICalDateTimeValue | null;
            ~~~~~
    The expected type comes from property 'start' which is declared here on type 'ICalEvent | ICalEventData'

index.ts:10:5 - error TS2322: Type 'DateTime' is not assignable to type 'ICalDateTimeValue | { (): ICalDateTimeValue | null; (end: ICalDateTimeValue | null): ICalEvent; } | null | undefined'.
  Type 'DateTime' is not assignable to type 'ICalLuxonDateTimeStub'.

10     end: endTime,
       ~~~

  node_modules/ical-generator/dist/index.d.cts:967:5
    967     end(): ICalDateTimeValue | null;
            ~~~
    The expected type comes from property 'end' which is declared here on type 'ICalEvent | ICalEventData'

Here is the setup to reproduce the issue:

package.json

{
  "name": "ical-hello-world",
  "version": "1.0.0",
  "devDependencies": {
    "@tsconfig/node18": "^2.0.0",
    "@types/luxon": "^3.3.0",
    "@types/node": "^18.15.13",
    "typescript": "^5.0.4"
  },
  "scripts": {
    "build": "tsc"
  },
  "dependencies": {
    "ical-generator": "^4.0.0",
    "luxon": "^3.3.0"
  }
}

tsconfig.json

{
  "extends": "@tsconfig/node18/tsconfig.json"
}

index.ts

import ical, {ICalCalendar} from 'ical-generator';
import {DateTime} from "luxon";

const calendar:ICalCalendar = ical({name: 'my first iCal'});
const startTime: DateTime = DateTime.now();
const endTime: DateTime = DateTime.now();

calendar.createEvent({
    start: startTime,
    end: endTime,
    summary: 'Example Event',
    description: 'It works ;)',
    location: 'my room',
    url: 'http://sebbo.net/'
});

[ismarslomic]

I recognised that this is caused by the strict type checking that is by default enabled in the tsconfig bases for node18. By overriding the strict flag to false I don't get the errors anymore.

Updated tsconfig.json

{
  "extends": "@tsconfig/node18/tsconfig.json",
  "compilerOptions": {
    "strict": false,
  }
}

[sebbo2002]

🎉 This issue has been resolved in version 4.1.0-develop.3 🎉

The release is available on:

• npm package (@next dist-tag)
• GitHub release
• v4.1.0-develop.3

Your semantic-release bot 📦🚀

[sebbo2002]

🎉 This issue has been resolved in version 4.1.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release
• v4.1.0

Your semantic-release bot 📦🚀