PART 2 Don't carry InvalidMagicNumber bytes read

[gnuish]

This changes the error. People probably would never want to know what the four bytes were, so there's a little less bloat this way. But in the rare case they do, it can still be manually read afterwards.

[ogham]

Thanks for these two!

People probably would never want to know what the four bytes were

I think the only reason I added this in was because I was still figuring out how to parse these files... and you know, since then, I haven’t needed to know what that number was once