dependencies are not added but replaced

[YuriGor]

Expected Behavior

I expect npm-add-dependencies will add dependencies, but not replace them

Actual Behavior

when i try to add some packages to the existing package.json, all the packages already listed in the corresponding section (devDependencies) disappear, so newly added packages fully replace old list.

Steps to Reproduce the Problem

before

{
  "name": "1-end",
  "version": "0.0.1",
  "license": "MIT",
  "scripts": {
    "build": "next build",
    "start": "next start",
    "dev": "next",
    "lint": "eslint components pages lib"
  },
  "dependencies": {
    "@material-ui/core": "^3.3.1",
    "next": "^7.0.2",
    "prop-types": "^15.6.2",
    "react": "^16.6.0",
    "react-dom": "^16.6.0",
    "react-jss": "^8.6.1"
  },
  "devDependencies": {
    "babel-eslint": "^10.0.1",
    "eslint": "^5.7.0",
    "eslint-config-airbnb": "^17.1.0",
    "eslint-plugin-import": "^2.14.0",
    "eslint-plugin-jsx-a11y": "^6.1.2",
    "eslint-plugin-react": "^7.11.1"
  }
}

command
npm-add-dependencies eslint-config-prettier eslint-plugin-prettier prettier --dev

after

{
  "name": "1-end",
  "version": "0.0.1",
  "license": "MIT",
  "scripts": {
    "build": "next build",
    "start": "next start",
    "dev": "next",
    "lint": "eslint components pages lib"
  },
  "dependencies": {
    "@material-ui/core": "^3.3.1",
    "next": "^7.0.2",
    "prop-types": "^15.6.2",
    "react": "^16.6.0",
    "react-dom": "^16.6.0",
    "react-jss": "^8.6.1"
  },
  "devDependencies": {
    "eslint-config-prettier": "^3.3.0",
    "eslint-plugin-prettier": "^3.0.0",
    "prettier": "^1.15.3"
  }
}

Specifications

• Version: 0.1.2, npm 6.4.1
• Platform: Ubuntu 18.04