Rollup duplicate dynamic imports bug

README.md

node build

(node:7660) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'id' of undefined
    at /repro/node_modules/rollup/dist/rollup.js:18666:69
    at Array.forEach (<anonymous>)
    at /repro/node_modules/rollup/dist/rollup.js:18654:45
    at Array.forEach (<anonymous>)
    at Chunk.setDynamicImportResolutions (/repro/node_modules/rollup/dist/rollup.js:18653:29)
    at /repro/node_modules/rollup/dist/rollup.js:18861:69
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:160:7)
    at Function.Module.runMain (module.js:703:11)
    at startup (bootstrap_node.js:193:16)
(node:7660) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:7660) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

node build codesplit

(node:8768) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'generateEntryExports' of undefined
    at /repro/node_modules/rollup/dist/rollup.js:19273:35
    at Array.forEach (<anonymous>)
    at /repro/node_modules/rollup/dist/rollup.js:19272:26
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:160:7)
    at Function.Module.runMain (module.js:703:11)
    at startup (bootstrap_node.js:193:16)
    at bootstrap_node.js:617:3
(node:8768) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:8768) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

node build external

OK

node build external codesplit

OK

build.js

const rollup = require('rollup')

const codesplit = process.argv.includes('codesplit')
const external = process.argv.includes('external')

const main = external ? 'main-external.js' : 'main.js'

if (codesplit) {
	rollup.rollup({
		input: [main],
		experimentalDynamicImport: true,
		experimentalCodeSplitting: true,
	}).then((bundle) => {
		bundle.write({
			dir: 'build',
			format: 'es',
		})
	})
} else {
	rollup.rollup({
		input: main,
		experimentalDynamicImport: true,
	}).then((bundle) => {
		bundle.write({
			file: 'build/main.js',
			format: 'es',
		})
	})
}

dependency.js

export default 'dependency'

main-external.js

import('./external-dependency').then(console.log)
import('./external-dependency').then(console.log)

main.js

import('./dependency').then(console.log)
import('./dependency').then(console.log)

package-lock.json

{
  "requires": true,
  "lockfileVersion": 1,
  "dependencies": {
    "rollup": {
      "version": "0.55.0",
      "resolved": "https://registry.npmjs.org/rollup/-/rollup-0.55.0.tgz",
      "integrity": "sha512-uCwDXz2qHQ0XsPekrLIeIEORSF32Zfk1H057ENgb+sj84m10pWaG2YGQSvF8kvyf0WLcrzk2TzYuC/+iZP4hyA=="
    }
  }
}

package.json

{
  "main": "main.js",
  "scripts": {
    "run": "node build"
  },
  "dependencies": {
    "rollup": "^0.55.0"
  }
}