Invalid byweekday conversion to string when initializing rrule with WeekdayStr ("MO", "TU") format

[vedranbasic]

Example:

const testRrule = new RRule({
                    "freq": 1,
                    "count": 20,
                    "bymonth": [3, 4, 5, 6],
                    "dtstart": new Date("2025-02-17T23:00:00.000Z"),
                    "interval": 1,
                    "byweekday": ["MO", "TU", "WE"]
                })


testRrule.options

/**
You get:
{
   ...,
   "byweekday":[0,1,2,],
   ...
}
*/

testRrule.toString()

/**
You get:
'DTSTART:20250217T230000Z\nRRULE:FREQ=MONTHLY;COUNT=20;BYMONTH=3,4,5,6;INTERVAL=1;BYDAY=undefined,undefined,undefined'
*/

I presume if options are proper after initializing rrule object with WeekdayStr (2 character strings) and converted to number, then toString() method might not be implemented properly for byweekday conversion to BYDAY.

If I initialized rrule.byweekday with numbers, it'll return allright in both cases. Example:

const testRrule = new RRule({
                    "freq": 1,
                    "count": 20,
                    "bymonth": [3, 4, 5, 6],
                    "dtstart": new Date("2025-02-17T23:00:00.000Z"),
                    "interval": 1,
                    "byweekday": [0,1,2]
                })

testRrule.options

/** 
You get:
{
   ...,
   "byweekday":[0,1,2,],
   ...
}
*/

testRrule.toString()

/**
You get:
'DTSTART:20250217T230000Z\nRRULE:FREQ=MONTHLY;COUNT=20;BYMONTH=3,4,5,6;INTERVAL=1;BYDAY=BYDAY=MO,TU,WE'
*/