code: function (index, blocks, out) {
          // only called in case of error
          var block = blocks[index];
          var msg = "Invalid HTML element syntax";
          if (block.code && block.code.match(/^<\/?@/)) {
              //when it starts with <@ or </@
              msg = "Invalid component attribute syntax";
          }
          this._logError(msg, block);
          return index;
      }
docs: Catches invalid element errors.
  @param {Array} blocks the full list of blocks.
  @param {Integer} index the index of the block to manage.
  @param {Array} out the output as an array of Node.
  @return {Integer} the index of the block where the function stopped or -1 if all blocks have been handled.