Use body for 204 if defined

KoaResource.js

@@ -215,11 +215,11 @@ class Resource {
           switch (ctx.state.__rMethod) {
             case 'index':
               ctx.status = 200;
-              ctx.body = [];
+              ctx.body = ctx.body || [];
               break;
             default:
               ctx.status = 200;
-              ctx.body = {};
+              ctx.body = ctx.body || {};
               break;
           }
           break;
@@ -800,19 +800,19 @@ class Resource {
           if (utils.get(ctx, 'state.session.constructor.name') !== 'ClientSession') ctx.state.session = await this.model.startSession();
           if (!ctx.state.session.inTransaction()) await ctx.state.session.startTransaction();
           writeOptions.session = ctx.state.session;
-          const errors = []
+          const errors = [];
           ctx.state.item = await Promise.all(ctx.state.item.map(item => item.save(writeOptions)))
             .catch((err) => {
-              errors.push(err)
+              errors.push(err);
             })
             .finally((result) => {
               if (errors.length) {
                 const err = new Error(`Error${errors.length > 1 ? 's' : ''} occured while trying to save document into database`);
                 err.name = 'DatabaseError';
-                err.errors = errors
-                throw err
+                err.errors = errors;
+                throw err;
               }
-              else return result
+              else return result;
             });
           await ctx.state.session.commitTransaction();
         }