fix error message

packages/growi-plugin-lsx/src/lib/routes/lsx.js

@@ -72,7 +72,7 @@ class Lsx {
    */
   static addReverseCondition(query, pagePath, optionsReverse){
     if (optionsReverse !== 'true' && optionsReverse !== 'false') {
-      throw new Error(`specified reverse is [' + ${optionsReverse} + '] : reverse are must be true or false`);
+      throw new Error(`specified reverse is '${optionsReverse}' : reverse are must be 'true' or 'false'`);
     }
     if(optionsReverse === 'true'){
       return query.sort({path: -1});