code: function validateSchema(schema, throwOrLogError) {
    var $schema = schema.$schema;
    if ($schema !== undefined && typeof $schema != 'string')
      throw new Error('$schema must be a string');
    $schema = $schema || this._opts.defaultMeta || defaultMeta(this);
    if (!$schema) {
      this.logger.warn('meta-schema not available');
      this.errors = null;
      return true;
    }
    var valid = this.validate($schema, schema);
    if (!valid && throwOrLogError) {
      var message = 'schema is invalid: ' + this.errorsText();
      if (this._opts.validateSchema == 'log') this.logger.error(message);
      else throw new Error(message);
    }
    return valid;
  }
docs: Validate schema
  @this   Ajv
  @param {Object} schema schema to validate
  @param {Boolean} throwOrLogError pass true to throw (or log) an error if invalid
  @return {Boolean} true if schema is valid