Peer/Dev Dependency Resolution Error

I have two packages in my monorepo, one of which dev-depends and peer-depends on the other. For this example, I’ve swapped out the real names with a and b.

a/package.json

{
  "name": "a",
  "version": "0.1.0",
  "main": "dist/cjs/index.js",
  "types": "dist/cjs/index.d.ts",
  "license": "Apache-2.0"
}

b/package.json

{
  "name": "b",
  "version": "0.1.0",
  "main": "dist/cjs/index.js",
  "types": "dist/cjs/index.d.ts",
  "license": "Apache-2.0",
  "devDependencies": {
    "a": "^0.1.0"
  },
  "peerDependencies": {
    "a": "^0.1.0"
  }
}

Upon bootstrapping I encounter the following error:

lerna ERR! npm install exited 1 in 'b'
lerna ERR! npm install stderr:
npm WARN ERESOLVE overriding peer dependency
npm WARN Found: a@undefined
npm WARN node_modules/a
npm WARN   peer a@"^0.1.0" from the root project
npm WARN 
npm WARN Could not resolve dependency:
npm WARN peer a@"^0.1.0" from the root project
npm ERR! code E404
npm ERR! 404 Not Found - GET https://registry.npmjs.org/a - Not found
npm ERR! 404 
npm ERR! 404  'a@^0.1.0' is not in the npm registry.
npm ERR! 404 You should bug the author to publish it (or use the name yourself!)
npm ERR! 404 
npm ERR! 404 Note that you can also install from a
npm ERR! 404 tarball, folder, http url, or git url.

It appears that––for some reason––the version of a is undefined, hence the package is not resolved. Because the package does not exist on NPM, the installation fails altogether.

Any help / advice would be greatly appreciated! Thank you!

lerna.json

{
  "$schema": "https://json.schemastore.org/lerna",
  "npmClient": "npm",
  "packages": ["packages/*"],
  "version": "0.1.0"
}

Your Environment

Executable	Version
lerna --version	3.22.1
npm --version	7.5.2
node --version	14.15.5

OS	Version
macOS Catalina	10.15.7

[iamtomcat]

If you’re using npm 7+ now, you just have to add "useWorkspaces": true to your lerna.json as npm has similar behaviour to yarn now.

[RonWang]

npm install --legacy-peer-deps lets my install pass without error. Environment: npm v7 on Windows.