Lerna, Preact-CLI, Workspaces Bug

reproduce.sh

#!/bin/sh

# Initializing Lerna
npx lerna init;

# Setup Workspaces
cat <<EOF > package.json
{
  "name": "root",
  "private": true,
  "devDependencies": {
    "lerna": "^3.20.2"
  },
  "workspaces": [
    "packages/mypack"
  ]
}
EOF

cat <<EOF > lerna.json
{
  "packages": [
    "packages/mypack"
  ],
  "version": "0.0.0",
  "npmClient": "yarn",
  "useWorkspaces": true
}
EOF

# Create default preact project
cd packages/;
npx preact create default mypack;

# Let lerna manage node_modules with bootstrap command below
rm -rf mypack/node_modules/;

# Bootstrap lerna
cd ..;
npx lerna bootstrap;

# Run build (this will print error)
npx lerna exec --scope mypack yarn build;