server bug

[felipexpert]

I am new to nodejs, and I got this error when configuring the web server:

$ gulp build-dist
/var/repo/Spika/web/node_modules/gulp-sass/index.js:66
let sassMap;
^^^

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:374:25)
at Object.Module._extensions..js (module.js:417:10)
at Module.load (module.js:344:32)
at Function.Module._load (module.js:301:12)
at Module.require (module.js:354:17)
at require (internal/module.js:12:17)
at Object. (/var/repo/Spika/web/gulpfile.js:7:12)
at Module._compile (module.js:410:26)
at Object.Module._extensions..js (module.js:417:10)