chore: add types to rollup configuration

Adds a type annotation to the rollup configuration.

Adds missing name to the custom discard CSS plugin.

rollup-plugin-discard-css.js

@@ -1,13 +1,18 @@
+/** @typedef {import('rollup').Plugin} RollupPlugin */
+
 /**
  * Tiny rollup plugin that discards CSS and ignores everything else.
  *
  * **Background**:
  *
  * `vue({ css: false })` wants another plugin to handle bundling the extracted CSS.
  * Since I want to bundle an unstyled version of my component, I want to throw that CSS away.
+ *
+ * @type {() => RollupPlugin}
  */
-export default function discardCss () {
+export function discardCss () {
   return {
+    name: 'discard-css',
     transform (_code, id) {
       return id.endsWith('css') ? { code: '', map: null } : null
     },

rollup.config.js

@@ -3,7 +3,9 @@ import postcss from 'rollup-plugin-postcss'
 import { terser } from 'rollup-plugin-terser'
 import vue from 'rollup-plugin-vue'
 
-import discardCss from './rollup-plugin-discard-css.js'
+import { discardCss } from './rollup-plugin-discard-css.js'
+
+/** @typedef {import('rollup').RollupOptions} RollupOptions */
 
 /*
 vue options:
@@ -33,7 +35,7 @@ const unstyledComponentPlugins = [
   terser(),
 ]
 
-export default [
+/** @type {RollupOptions[]} */ const options = [
   {
     input: 'src/index.js',
     output: {
@@ -62,3 +64,5 @@ export default [
     plugins: unstyledComponentPlugins,
   },
 ]
+
+export default options