PartitionDurationFormatPattern need to handle undefined field in duration

[FrankYFTang]

In the proposal, there are two places calling PartitionDurationFormatPattern with the value return by ToPartialDuration.

https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat.prototype.format

1.4.3 Intl.DurationFormat.prototype.format ( duration )
...
3. Let record be ? ToPartialDuration(duration).
4. Let formatted be ? PartitionDurationFormatPattern(df, record).

and
https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat.prototype.formatToParts

1.4.4 Intl.DurationFormat.prototype.formatToParts ( duration )
...
3. Let record be ? ToPartialDuration(duration).
4. Let formatted be ? PartitionDurationFormatPattern(df, record).

Notice, in ToPartialDuration
https://tc39.es/proposal-temporal/#sec-temporal-topartialduration
some of the field might be "undefined"

But inside 1.1.2 PartitionDurationFormatPattern ( durationFormat, duration )
https://tc39.es/proposal-intl-duration-format/#sec-partitiondurationformatpattern

step 2-k-i

i. Set value to duration.[[Microseconds]] + duration.[[Nanoseconds]] / 1000.

but either duration.[[Microseconds]] and duration.[[Nanoseconds]] could be undefined.

and step 2-k-ii-1

1. Set value to duration.[[Milliseconds]] + value / 1000.

duration.[[Milliseconds]] could be undefined
and step 2-k-ii-2-a

a. Set value to duration.[[Seconds]] + value / 1000.

duration.[[Seconds]] could be undefined

and step 2-l-i

i. Set value to duration.[[<valueSlot>]].

any duration.[[]] could be undefined and resulting value is undefined
but then 2-p

p. Let num be ! FormatNumeric(durationFormat.[[NumberFormat]], value).

will pass undefined as 2nd argument to FormatNumeric
and step 2-t-ii

ii. Let prv be ! ResolvePlural(pr, value).

will pass undefined as 2nd argument to ResolvePlural

I don't think any of above are correct.

@sffc @ryzokuken

[sffc]

Discussion 2021-01-13: https://github.com/tc39/ecma402/blob/master/meetings/notes-2022-01-13.md#partitiondurationformatpattern-need-to-handle-undefined-field-in-duration-90

Conclusion: Treat undefined as 0.