errors when Install ssm using the codes: sudo npm install -g

[Spatial-R]

/usr/local/lib/node_modules/npm/bin/npm-cli.js:85
let notifier = require('update-notifier')({pkg})
^^^

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 Function.Module.runMain (module.js:442:10)
at startup (node.js:136:18)
at node.js:966:3