code: function validateConfigSchema(config, source = null) {
      validateSchema = validateSchema || ajv.compile(configSchema);
  
      if (!validateSchema(config)) {
          throw new Error(`ESLint configuration in ${source} is invalid:\n${formatErrors(validateSchema.errors)}`);
      }
  
      if (Object.hasOwnProperty.call(config, "ecmaFeatures")) {
          emitDeprecationWarning(source, "ESLINT_LEGACY_ECMAFEATURES");
      }
  }
docs: Validates the top level properties of the config object.
  @param {Object} config The config object to validate.
  @param {string} source The name of the configuration source to report in any errors.
  @returns {void}