SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode

Got this while trying to do a fresh install of Spark. Not sure if it’s a Spark or Mix issue. Thanks for any help!

node v4.7.3 npm 4.1.2 spark-installer 1.2.0 OSX 10.11.6

Would you like to compile your assets? (yes/no) [yes]:
 > yes

Running Build Script...

> @ dev /sites
> node node_modules/cross-env/bin/cross-env.js NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js

/sites/node_modules/laravel-mix/setup/webpack.config.js:120
        let extractPlugin = new plugins.ExtractTextPlugin(
        ^^^

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 Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at requireConfig (/sites/node_modules/webpack/bin/convert-argv.js:96:18)
    at /sites/node_modules/webpack/bin/convert-argv.js:109:17
    at Array.forEach (native)

[orrd]

For anyone having this issue with Homestead or similar environments, I was unable to get Node to upgrade using the typical instructions which are usually

sudo npm install -g npm sudo npm install -g n sudo n stable

That still wasn’t changing the version of Node that was being used. I finally found that you have change the /usr/bin/node symlink like this:

sudo ln -sf /usr/local/n/versions/node/<VERSION>/bin/node /usr/bin/node

Use whatever the highest version is in place of “<VERSION>” from your install options in /usr/local/n/versions/node.

[JeffreyWay]

Bump your Node dependency. You have 4.7.3, when the current version is 7.4.