I don't understand how to import a random npm library in Svelte.

Take the scrapegoat library for example, a library to read CalDAV objects. I created a brand new Svelte project:

$ npx degit sveltejs/template my-svelte-project
$ cd my-svelte-project/
$ npm install
$ npm install -D scrapegoat

Not sure if it should be added to the devDependencies but it doesn't seem to make a lot of difference if it is not. Now, in the src/App.svelte I add this singe line in the existing <script> tag.

import scrapegoat from 'scrapegoat'

Running npm run dev throws the following error:

[!] Error: Unexpected token (Note that you need @rollup/plugin-json to import JSON files)
node_modules/scrapegoat/package.json (2:9)
1: {
2:   "_from": "scrapegoat@^2.0.0",
            ^
3:   "_id": "scrapegoat@2.0.0",
4:   "_inBundle": false,
Error: Unexpected token (Note that you need @rollup/plugin-json to import JSON files)
    at error (node_modules/rollup/dist/shared/rollup.js:158:30)
    at Module.error (node_modules/rollup/dist/shared/rollup.js:12420:16)
    at Module.tryParse (node_modules/rollup/dist/shared/rollup.js:12823:25)
    at Module.setSource (node_modules/rollup/dist/shared/rollup.js:12726:24)
    at ModuleLoader.addModuleSource (node_modules/rollup/dist/shared/rollup.js:22197:20)

This is what I understood from Rich Harris' reply but I am clearly missing something.