`Sectors::get` accesses unclaimed/uninitialized memory

Affected versions of this crate arbitrarily calls Vec::set_len to increase length of a vector without claiming more memory for the vector. Affected versions of this crate
also calls user-provided Read on the uninitialized memory of the vector that was
extended with Vec::set_len.

This can overwrite active entities in adjacent heap memory and seems to be a major security issue. Also, calling user-provided Read on uninitialized memory is defined as UB in Rust.