fix toJSON value

src/types/YArray.js

@@ -2,7 +2,6 @@
  * @module YArray
  */
 
-import { useSearchMarker } from 'tests/testHelper.js'
 import {
   YEvent,
   AbstractType,
@@ -10,6 +9,7 @@ import {
   callTypeObservers,
   transact,
   ListIterator,
+  useSearchMarker,
   UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'
 

src/utils/ListIterator.js

@@ -430,6 +430,6 @@ const sliceArrayContent = (itemcontent, start, len) => {
  * @param {Array<any>} added
  */
 const concatArrayContent = (content, added) => {
-  content.push(added)
+  content.push(...added)
   return content
 }