XO0169: match or select arms separated by `,` instead of newlines

match and select arms are separated by newlines, not commas, so arms read like statements. Remove the comma. See core 3.5.

Example

fn f(b: Bool) -> Int {
  match b {
    true => 1,
    false => 2
  }
}

Fix

fn f(b: Bool) -> Int {
  match b {
    true => 1
    false => 2
  }
}

Run xo explain XO0169 for this text in a terminal, or see section 10.6 of the specification.