core/tsconfig.json

{
  "compilerOptions": {
    "baseUrl": ".",
    "outDir": "dist",
    "sourceMap": false,
    "target": "esnext",
    "module": "esnext",
    "moduleResolution": "node",
    // "declaration": true,
    "allowJs": false,
    "noUnusedLocals": true,
    "strictNullChecks": true,
    "noImplicitAny": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "lib": [
      "esnext",
      "dom"
    ],
    "rootDir": ".",
    "paths": {
      "@vue/core": ["packages/core/src"],
      "@vue/observer": ["packages/observer/src"],
      "@vue/scheduler": ["packages/scheduler/src"]
    }
  },
  "include": [
    "packages/global.d.ts",
    "packages/*/src"
  ]
}