util: do not parse truncated input on append failure

[prownd]

fjson_object_from_fd() ignored the return value of printbuf_memappend(). If an append failed (e.g. out of memory) it went on to parse whatever had been accumulated so far, silently returning an object built from truncated input. Check the result and fail instead.

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Summary by cubic

Fixes fjson_object_from_fd() so it no longer parses truncated input when printbuf_memappend() fails. Previously the return value was ignored, so on append failure (e.g., out of memory) it silently returned an object built from incomplete data; now it logs an error, frees the buffer, and returns NULL.

^{Written for commit eae5c6a. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

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_{Re-trigger cubic}