How errors pop out in my js-mode

errors.js

// Showing how errors pop out in my js-mode standard indenting:
// (https://github.com/thomblake/js-mode)
// (courtesy of https://gist.github.com/357981 for the excellent examples)

// error in standard style
var a = "ape",
    b = "bat",
    c = "cat",
    d = "dog"
e = "elf",
f = "fly",
g = "gnu",
h = "hat",
i = "ibu";

// error in comma-first style
var a = "ape"
  , b = "bat"
  , c = "cat"
  , d = "dog"
e = "elf"
  , f = "fly"
  , g = "gnu"
  , h = "hat"
  , i = "ibu"
;