[RaphaelFakhri]

Motivation

A controlled List.AccordionGroup with expandedId={0} does not expand the accordion with id={0}. The group resolves the expanded ID with expandedIdProp || expandedId, so 0 falls back to the internal state, which a controlled group never updates. Indexes from .map are a common source of IDs, so the first accordion in such a list can never be opened.

This change uses ?? so only undefined falls back to the internal state. Uncontrolled groups behave as before.

Related issue

id={0} support was added in #3936 (fixing #3902), but the controlled expandedId path still treats 0 as missing. Fixes #5144

Screenshots / Videos

Not applicable. The change affects which accordion expands, not styling.

Test plan

1. Render a controlled group:

   const [expandedId, setExpandedId] = React.useState<number | string>(0);
   
   <List.AccordionGroup expandedId={expandedId} onAccordionPress={setExpandedId}>
     <List.Accordion title="First" id={0}>
       <List.Item title="First item" />
     </List.Accordion>
     <List.Accordion title="Second" id={1}>
       <List.Item title="Second item" />
     </List.Accordion>
   </List.AccordionGroup>

2. Confirm that "First" is expanded on mount.

3. Press "Second", then press "First" again, and confirm that "First" expands.

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Found potential problems with the pull request:

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