tsconfig file can not support extends

[snowyu]

like this.

// tsconfig.json
{
  "extends": "./tsconfig.base",
  "exclude": [
    "test.ts",
    "**/*.spec.ts"
  ]
}

// tsconfig.base.json
{
  "compilerOptions": {
    "sourceMap": true,
    "target": "es5",
    "strict": true,
    "noImplicitAny": false,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "module": "es2015",
    "lib": [
      "es2015",
      "es2017",
      "dom"
    ],
    "moduleResolution": "node",
    "baseUrl": "src",
    "paths": {
      "@plugins/*": ["plugins/*"],
    }
  },
  "include": [
    "./src/**/*"
  ]
}