Missing dependency on preact / react (ghost dependency)

package.json の依存関係の宣言と、レポートに記載されている preact および react のインポートパスを調査します。Yarn Plug'n'Play で失敗を再現し、その後 issue 内の依存関係の選択肢を比較します。パッケージが実行時要件を正しく宣言し、サポート対象のどちらのライブラリでも ghost-dependency エラーが発生しなければ完了です。

This module tries to import / require from preact, but does not declare it as a dependency in its package.json (a ghost dependency). This is an error, yarn requires all dependency to be listed properly:

Module not found: Error: Can't resolve 'preact' in 'C:\Users\user\AppData\Local\Yarn\Berry\cache\htm-npm-3.1.1-e3b831f850-10.zip\node_modules\htm\preact'
resolve 'preact' in 'C:\Users\user\AppData\Local\Yarn\Berry\cache\htm-npm-3.1.1-e3b831f850-10.zip\node_modules\htm\preact'
  Parsed request is a module
  using description file: C:\Users\user\AppData\Local\Yarn\Berry\cache\htm-npm-3.1.1-e3b831f850-10.zip\node_modules\htm\preact\package.json (relative path: .)
    Field 'browser' doesn't contain a valid alias configuration
    resolve as module
      request is not managed by the pnpapi
        htm tried to access preact, but it isn't declared in its dependencies; this makes the require call ambiguous and unsound.
        Required package: preact
        Required by: htm@npm:3.1.1 (via C:\Users\user\AppData\Local\Yarn\Berry\cache\htm-npm-3.1.1-e3b831f850-10.zip\node_modules\htm\preact\)
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/@bpmn-io-diagram-js-ui-npm-0.2.3-01795dd8e0-10.zip/node_modules/@bpmn-io/diagram-js-ui/lib/index.js 1:0-34 1:0-34
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/diagram-js-npm-15.2.4-de7db86f90-10.zip/node_modules/diagram-js/lib/ui/index.js 1:0-39 1:0-39
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/diagram-js-npm-15.2.4-de7db86f90-10.zip/node_modules/diagram-js/lib/features/popup-menu/PopupMenu.js 1:0-4:18 132:2-8 133:4-8 278:2-8  
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/diagram-js-npm-15.2.4-de7db86f90-10.zip/node_modules/diagram-js/lib/features/popup-menu/index.js 1:0-36 12:23-32
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/bpmn-js-npm-18.2.0-5474b88486-10.zip/node_modules/bpmn-js/lib/features/align-elements/index.js 3:0-65 13:4-19
 @ ../../../../../../AppData/Local/Yarn/Berry/cache/bpmn-js-npm-18.2.0-5474b88486-10.zip/node_modules/bpmn-js/lib/Modeler.js 12:0-60 167:2-21
 @ ./src/bpmn-editor/render-bpmn-editor.ts 7:0-48 33:31-41
 @ ./src/bpmn-editor/index.ts 1:0-40 1:0-40

The same goes for react. Possible ways how the dependencies could be fixed:

• declare both react and preact as dependencies (will always install both preact and react)
• declare both react and preact as optional peer dependencies (preferred) (will force users to install both react and preact)
• create 2 separate NPM packages, so that each package can declare its dependencies properly

Workaround

For people affected: You can add the following bandage aid to fix the declared dependencies (file .yarnrc.yml):

packageExtensions:
  htm@*:
    peerDependencies:
      preact: "*"
      react: "*"
    peerDependenciesMeta:
    preact:
      optional: true
    react:
      optional: true