Fix check for null pointer in query deserialization

[pavlosantoniou]

In function 'query_from_capnp' in file 'sm/serialization/query.cc', the pointer 'existing_offset_buffer_size_ptr' is checked for a null value instead of 'existing_buffer_size_ptr' before dereferencing the latter.

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TYPE: BUG
DESC: Fix check for null pointer in query deserialization

[Shelnutt2]

@pavlosantoniou Thank you for catching this and the fix. I'm curious, did you experience a crash related to this? Are you using TileDB Cloud or are you using the serialization calls independently?

Also please don't worry about the add_history_commit CI failure, its a relatively new action we have and seems to not work because of PR coming from a forked repo, we'll check on that separately.

[pavlosantoniou]

@Shelnutt2 you are welcome, I stumbled upon this while exploring the code.

[joe-maley]

Thank you @pavlosantoniou!