Function expected_embeddings_size 

pub fn expected_embeddings_size(
    dtype: &str,
    n: usize,
    dim: usize,
) -> Option<usize>

Expected size of the embeddings section for a given dtype. None for an unknown dtype AND when n * dim overflows: both come from an untrusted header, and a wrapped product would let a hostile file claim a huge corpus behind a tiny section (mutation-fuzz finding).