Format alternate nested arrays without dash

[nhooyr]

Will improve our xerrors formatting a lot.

Though tbh it’d seem really bizarre to not have fields for loc and whatnot cause the number of fields is fixed and it’s semantically a map.

[nhooyr]

So

  -
    - a
    - b
    - c
  -
    - a
    - b
    - c

would become

  - a
    b
    c
  - a
    b
    c

[nhooyr]

TBH that's a lot harder to read than keeping them on separate lines.

[nhooyr]

I think the following is best:

  - - a
    - b
    - c
  - - a
    - b
    - c

[nhooyr]

Nvm, that's horrendous too. I'm gonna leave it as is for now.