Unable to use the sentry/browser and the sentry/hub

I’m trying to use @sentry/browser and @sentry/hub in a project but when I use it, the resultant script throws the following error.

index.js:3 Uncaught TypeError: r.__exportStar is not a function
    at Object.47../async (index.js:3)
    at c (_prelude.js:1)
    at _prelude.js:1
    at Object.37.@sentry/utils (scope.js:3)
    at c (_prelude.js:1)
    at _prelude.js:1
    at Object.36../hub (index.js:2)
    at c (_prelude.js:1)
    at _prelude.js:1
    at Object.38.@sentry/hub (index.js:3)

My toolchain is a using Browserify, Babel and Grunt and I’m importing Sentry like this:

import { BrowserClient } from "@sentry/browser"
import { Hub } from "@sentry/hub"

Do I need to transpile something or is this a TypeScript thing?

Why am I unable to use this? Thank you.