Don't throw error in development mode

[Vitegor]

Environment (Windows 7):

1. package.json

{
  "name": "parcel_vue",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "dev": "parcel src/index.html --open --no-cache",
    "build": "parcel build src/index.html --no-minify --no-cache --public-url ./",
    "prod": "parcel build src/index.html  --no-cache --public-url ./"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "moment": "^2.20.1",
    "vue": "^2.5.13"
  },
  "devDependencies": {
   
 "parcel-bundler": "^1.5.1",
    "parcel-plugin-typescript": "^0.6.1-next.2",
    "typescript": "^2.7.1"
  }
}

2. index.ts

var getMessage = (name: string): string => {
    return `Hello, ${name}!`;
}
console.log(getMessage("12345"));

3. tsconfig.json

{
  "parcelTsPluginOptions": {
    "transpileOnly": false
  }
}

I run npm run dev, and its builds succesfull. If i change console.log(getMessage("12345")) to console.log(getMessage(12345)) its builds succesfull yet, without error message.