update parent._map when splitting an item

tests/testHelper.js

@@ -9,7 +9,6 @@ import {
 
 import * as t from 'lib0/testing.js'
 import * as prng from 'lib0/prng.js'
-import { createMutex } from 'lib0/mutex.js'
 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'
 import * as syncProtocol from 'y-protocols/sync.js'

tests/y-array.tests.js

@@ -335,8 +335,8 @@ const arrayTransactions = [
 /**
  * @param {t.TestCase} tc
  */
-export const testRepeatGeneratingYarrayTests20 = tc => {
-  applyRandomTests(tc, arrayTransactions, 3)
+export const testRepeatGeneratingYarrayTests4 = tc => {
+  applyRandomTests(tc, arrayTransactions, 4)
 }
 
 /**