fix(realtime): handle null at convertChangeData

[rbasto1]

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

When a record is changed, and that record is used by a row-level access policy, the record arriving in the subscription can be null. When convertChangeData tries to Object.keys(record), we get error:

@supabase_supabase-js.js?v=02935ef6:1614 Uncaught TypeError: Cannot convert undefined or null to object
    at Object.keys (<anonymous>)
    at convertChangeData (@supabase_supabase-js.js?v=02935ef6:1614:17)
    at _RealtimeChannel._getPayloadRecords (@supabase_supabase-js.js?v=02935ef6:2552:21)
    at @supabase_supabase-js.js?v=02935ef6:2438:83
    at Array.map (<anonymous>)
    at _RealtimeChannel._trigger (@supabase_supabase-js.js?v=02935ef6:2425:10)
    at @supabase_supabase-js.js?v=02935ef6:2947:96
    at Array.forEach (<anonymous>)
    at @supabase_supabase-js.js?v=02935ef6:2947:67
    at Serializer.decode (@supabase_supabase-js.js?v=02935ef6:1536:14)

What is the new behavior?

If the record is null, return an empty object to the caller of convertChangeData.

Additional context

Updated also the signature of the call to reflect that record can also be null.

[filipecabaco]

are you able to replicate it in unit tests so we can guarantee good coverage?

[rbasto1]

@filipecabaco done

[github-actions]

🚀 Preview Release Status

false

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_{Last updated: 2025-09-20T08:38:52Z}

[filipecabaco]

thank you 🙏