Function maybe_read_in_chunks 

fn maybe_read_in_chunks<R: Read + ?Sized>(
    len: usize,
    r: &mut R,
) -> Result<Vec<u8>, Error>

Reads data from the reader r in chunks if the length len exceeds a predefined chunk size.

This approach avoids preallocating a large buffer upfront, which is crucial for handling potentially large or untrusted input sizes efficiently and safely.