validateBundles does not print conflicting names

[lukaw3d]

🐛 bug report

new Set(bundleNames) and new Set(unique(bundleNames)) both remove duplicates so setDifference is empty

parcel/packages/core/core/src/requests/BundleGraphRequest.js

Lines 485 to 488 in f53f450

	'Bundles must have unique name. Conflicting names: ' +
	[
	...setDifference(new Set(bundleNames), new Set(unique(bundleNames))),
	].join(),

🎛 Configuration (.babelrc, package.json, cli command)

{
  "your": { "config": "here" }
}

🤔 Expected Behavior

😯 Current Behavior

💁 Possible Solution

🔦 Context

💻 Code Sample

🌍 Your Environment

Software	Version(s)
Parcel
Node
npm/Yarn
Operating System