title: Watch Ignore Plugin has been initialized using an options object that does not match the API schema
body: <pre><code>Webpack: Starting ...
  ui/node_modules/schema-utils/dist/validate.js:104
      throw new _ValidationError.default(errors, schema, configuration);
      ^
  
  ValidationError: Invalid options object. Watch Ignore Plugin has been initialized using an options object that does not match the API schema. {
    schema: {
      title: 'WatchIgnorePluginOptions',
      type: 'object',
      additionalProperties: false,
      properties: {
        paths: {
          description: 'A list of RegExps or absolute paths to directories or files that should be ignored.',
          type: 'array',
          items: {
            description: 'RegExp or absolute path to directories or files that should be ignored.',
            anyOf: [ [Object], [Object] ]
          },
          minItems: 1
        }
      },
      required: [ 'paths' ]
    },
    headerName: 'Watch Ignore Plugin',
    baseDataPath: 'options',
    postFormatter: null
  }
  </code></pre>
  <p>It is thrown with the following configuration:</p>
  <pre><code>new webpack.WatchIgnorePlugin([ 'src/test' ])
  </code></pre>
  <p>The version of webpack is &quot;^5.0.0-rc.6&quot;.
  According to constructor</p>
  <pre><code>constructor(paths: Array&lt;string | RegExp&gt;)
  </code></pre>
  <p><code>[ 'src/test' ]</code> should be fine. Where I did a mistake?</p>