fix #1379 decodecorpus was generating one extraneous byte when `nbSeq==0`. This is disallowed by the specification. The reference decoder was just skipping the extraneous byte. It is now stricter, and flag such situation as an error.
fix #1379 decodecorpus was generating one extraneous byte when `nbSeq==0`. This is disallowed by the specification. The reference decoder was just skipping the extraneous byte. It is now stricter, and flag such situation as an error.