Wrong return type from RRule.fromString(...).options (bad null values in ParsedOptions)

[ghost]

We use the following: RRule.fromString(ruleString) with ruleString = 'DTSTART:19760101T000000 FREQ=DAILY;INTERVAL=1;BYHOUR=0;BYMINUTE=0;BYSECOND=0"'

The TS types claim that the returntype of the options field is a ParsedOptions:

rrule/src/types.ts

Lines 59 to 72 in 9f2061f

	export interface ParsedOptions extends Options {
	dtstart: Date
	wkst: number
	bysetpos: number[]
	bymonth: number[]
	bymonthday: number[]
	bynmonthday: number[]
	byyearday: number[]
	byweekno: number[]
	byweekday: number[]
	byhour: number[]
	byminute: number[]
	bysecond: number[]
	}

However, a handful of these fields will be null which isn't allowed by the typing.
This trips our linter (eslint).

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In our case, these fields are problematic (null, but not typed as such):

• bysetpos
• bymonth
• byyearday
• byweekno
• byweekday

But other fields are likely also affected by other rrules.