Reproducible scenario

buggy.js

var x = {
  a: 1,
  b 2
}

scenarion.js

let sandbox = Cu.Sandbox("http://example.com")
let { loadSubScript } = Cc['@mozilla.org/moz/jssubscript-loader;1'].
                     getService(Ci.mozIJSSubScriptLoader);

function load(uri) {
  try {
    loadSubScript(uri, sandbox)
  } catch (error) {
    return error
  }
}

let error = load("file:///path/to/buggy.js")

error.lineNumber   // => 3
error.fileName     // => Scratchpad/2 -> file:///Users/gozala/buggy.js
error.stack        // => ""


// Stack should contain path to error.fileName and error.lineNumber