Unexpected side effect in "computedName" computed property

[artnikbrothers]

Tell us about your environment

• ESLint Version: 4.18.1
• eslint-plugin-vue Version: 4.3.0
• Node Version: v9.4.0

Please show your full configuration:

module.exports = {
  root: true,
  parserOptions: {
    parser: 'babel-eslint',
    ecmaVersion: 2017,
    sourceType: 'module'
  },
  env: {
    browser: true,
    node: true
  },
  extends: ['plugin:vue/recommended'],
  // required to lint *.vue files
  plugins: [
    'vue'
  ],
  // add your custom rules here
  rules: {
    // allow paren-less arrow functions
    'arrow-parens': 0,
    // allow async-await
    'generator-star-spacing': 'off',
    // allow debugger during development
    'no-debugger': process.env.NODE_ENV === 'production' ? 'error' : 'off',
    // allow assignment in return statement
    'no-return-assign': 0,
    "vue/order-in-components": ["error", {
      order: [
        "el",
        "name",
        "parent",
        "functional",
        "mixins",
        ["delimiters", "comments"],
        ["components", "directives", "filters"],
        "extends",
        "inheritAttrs",
        "model",
        ["props", "propsData"],
        "data",
        "computed",
        "watch",
        "methods",
        "LIFECYCLE_HOOKS",
        ["template", "render"],
        "renderError"
      ]
    }]
  },
  globals: {
    // OT: false
  }
}

What did you do? Please include the actual source code causing the issue.

data () {
  return {
    someArray: [1, 2, 3]
  }
},
computed: {
  foo () {
    this.someArray.forEach(arr => console.log(arr)) // Unexpected side effect in "foo" computed property
  }
}

What actually happened? Please include the actual, raw output from ESLint.
Unexpected side effect in "foo" computed property

[michalsnik]

Addressed in #464. Closing in favor of #420