$yarn run firefox                                                                                                                                                 yarn run v0.17.10
$ node bin/firefox-driver --start 
/home/andrei/Dev/debugger.html/debugger.html/bin/firefox-driver.js:31
  let binary = new firefox.Binary();
  ^^^

SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:373:25)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)
    at startup (node.js:139:18)
    at node.js:974:3
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
$node --version                                                                                                                                                   v4.6.1

$ndenv local v6.9.2
$node --version 
v6.9.2
$yarn run firefox                                                                                                                                                 yarn run v0.17.10
$ node bin/firefox-driver --start 
/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/lib/promise.js:2517
        throw error;
        ^

Error: Server terminated early with status 1
    at Error (native)
    at earlyTermination.catch.e (/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/remote/index.js:252:52)
    at process._tickCallback (internal/process/next_tick.js:103:7)
From: Task: WebDriver.createSession()
    at Function.createSession (/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/lib/webdriver.js:777:24)
    at Function.createSession (/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/firefox/index.js:640:55)
    at createDriver (/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/index.js:167:33)
    at Builder.build (/home/andrei/Dev/debugger.html/node_modules/selenium-webdriver/index.js:642:16)
    at start (/home/andrei/Dev/debugger.html/bin/firefox-driver.js:59:6)
    at Object.<anonymous> (/home/andrei/Dev/debugger.html/bin/firefox-driver.js:65:18)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.