reinstalling "ng new" project: yarn start error=required package: @angular-devkit/architect (via "@angular-devkit/architect") not declared

[laurencefass]

Do you want to request a feature or report a bug?

critical bug

What is the current behavior?

1. install new angular project with ng new.
2. enter ng-new folder.
3. set yarn to 2.0 in folder according to: https://next.yarnpkg.com/getting-started/install
4, remove node_modules folder and any .lock files
4. run yarn install again.
5. run yarn start `( e.g. set to ng serve --host 0.0.0.0 --port 3605 --disable-host-check --public-host https://angular.syntapse.co.uk/ng-new/ in package.json)`

Result:

An unhandled exception occurred: Something that got detected as your top-level application (because it doesn't seem to belong to any package) tried to access a package that is not declared in your dependencies

Required package: @angular-devkit/architect (via "@angular-devkit/architect")
Required by: /app/angular/ng-new/node_modules/@angular-devkit/build-angular/src/dev-server/index.js

Require stack:
- /app/angular/ng-new/node_modules/@angular-devkit/build-angular/src/dev-server/index.js
- /app/angular/ng-new/.yarn/cache/@angular-devkit-architect-npm-0.803.20-b002c42256-1.zip/node_modules/@angular-devkit/architect/node/node-modules-architect-host.js
- /app/angular/ng-new/.yarn/cache/@angular-devkit-architect-npm-0.803.20-b002c42256-1.zip/node_modules/@angular-devkit/architect/node/index.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/models/architect-command.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/commands/serve-impl.js
- /app/angular/ng-new/.yarn/cache/@angular-devkit-schematics-npm-8.3.20-71c0eb71a3-1.zip/node_modules/@angular-devkit/schematics/tools/export-ref.js
- /app/angular/ng-new/.yarn/cache/@angular-devkit-schematics-npm-8.3.20-71c0eb71a3-1.zip/node_modules/@angular-devkit/schematics/tools/index.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/utilities/json-schema.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/models/command-runner.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/lib/cli/index.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/lib/init.js
- /app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/bin/ng
See "/tmp/ng-EmIJni/angular-errors.log" for further details

What is the expected behavior?

yarn start should work without dependency issues on a project created with ng new which works ok with yarn v1 in normal mode.

Please mention your node.js, yarn and operating system version.

bash-4.4# yarn --version
2.0.0-rc.19
bash-4.4# node --version
v11.1.0
bash-4.4# cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.8.1

[laurencefass]

/tmp/ng-EmIJni/angular-errors.log

[error] Error: Could not find module "@angular-devkit/build-angular" from "/app/angular/ng-new".
    at Object.resolve (/app/angular/ng-new/.yarn/cache/@angular-devkit-core-npm-8.3.20-cc9c74017d-1.zip/node_modules/@angular-devkit/core/n$    at WorkspaceNodeModulesArchitectHost.resolveBuilder (/app/angular/ng-new/.yarn/cache/@angular-devkit-architect-npm-0.803.20-b002c42256-$    at ServeCommand.initialize (/app/angular/ng-new/.yarn/unplugged/@angular-cli-npm-8.3.20-0750f884fd/node_modules/@angular/cli/models/arc$    at process._tickCallback (internal/process/next_tick.js:43:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:763:11)
    at startup (internal/bootstrap/node.js:308:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:878:3)

[merceyz]

PnP support for angular is tracked in yarnpkg/berry#266