Start failed (maybe due to missing mongodb)

[scriptzteam]

Builded while mongodb missing but could casue it this?

**~/bitdb/bitd# npm start**

> [email protected] start /root/bitdb/bitd
> node index

/root/bitdb/bitd/bit.js:41
        let hash = message.toString('hex')
        ^^^

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 Object.<anonymous> (/root/bitdb/bitd/index.js:1:73)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)

npm ERR! Linux 4.15.0-23-generic
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "start"
npm ERR! node v4.5.0
npm ERR! npm  v2.15.9
npm ERR! code ELIFECYCLE
npm ERR! [email protected] start: `node index`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] start script 'node index'.