### Elasticsearch Version

8.6.0

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

docker-image = docker.elastic.co/elasticsearch/elasticsearch:8.6

### Problem Description

We are trying to migrate from Elasticsearch 6.7.1 to Elasticsearch 8.6.0.

With the same document we always get IndexOutOfBoundsException while trying to fetch innerhits in Elasticsearch 8.6.0. Everything works fine in Elasticsearch 6.7.1.


### Steps to Reproduce

[elasticsearch_6.7.1 (1).txt](https://github.com/elastic/elasticsearch/files/10466823/elasticsearch_6.7.1.1.txt)
[elasticsearch_8.6.0.txt](https://github.com/elastic/elasticsearch/files/10466824/elasticsearch_8.6.0.txt)


### Logs (if relevant)

`{"@timestamp":"2023-01-20T13:39:21.170Z", "log.level": "WARN", "message":"path: /test/_search, params: {index=test}", "ecs.version": "1.2.0","service.name":"ES_ECS","event.dataset":"elasticsearch.server","process.thread.name":"elasticsearch[es01][search][T#10]","log.logger":"rest.suppressed","elasticsearch.cluster.uuid":"T3_Kb_fZTOORKN7Bn5jz2g","elasticsearch.node.id":"fESFHfZ-RxuDaPIIKhOoNA","elasticsearch.node.name":"es01","elasticsearch.cluster.name":"es_alex","error.type":"org.elasticsearch.action.search.SearchPhaseExecutionException","error.message":"all shards failed","error.stack_trace":"Failed to execute phase [query], all shards failed; shardFailures {[fESFHfZ-RxuDaPIIKhOoNA][test][0]: org.elasticsearch.transport.RemoteTransportException: [es01][172.27.0.2:9300][indices:data/read/search[phase/query]]\nCaused by: org.elasticsearch.search.fetch.FetchPhaseExecutionException: Fetch Failed [Error running fetch phase for doc [73]]\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:181)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.execute(FetchPhase.java:93)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.executeFetchPhase(SearchService.java:659)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.executeQueryPhase(SearchService.java:634)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.lambda$executeQueryPhase$2(SearchService.java:489)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionRunnable.lambda$supply$0(ActionRunnable.java:47)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionRunnable$2.doRun(ActionRunnable.java:62)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:33)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:769)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)\n\tat java.base/java.lang.Thread.run(Thread.java:833)\nCaused by: org.elasticsearch.search.fetch.FetchPhaseExecutionException: Fetch Failed [Error running fetch phase for doc [43]]\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:181)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.execute(FetchPhase.java:93)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.subphase.InnerHitsPhase.hitExecute(InnerHitsPhase.java:76)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.subphase.InnerHitsPhase$1.process(InnerHitsPhase.java:52)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:177)\n\t... 13 more\nCaused by: java.lang.IndexOutOfBoundsException: Index: 43, Size: 1\n\tat java.base/java.util.Collections$SingletonList.get(Collections.java:4959)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.prepareNestedHitContext(FetchPhase.java:466)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.prepareHitContext(FetchPhase.java:312)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:165)\n\t... 17 more\n}\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseFailure(AbstractSearchAsyncAction.java:728)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction.executeNextPhase(AbstractSearchAsyncAction.java:418)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseDone(AbstractSearchAsyncAction.java:760)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction.onShardFailure(AbstractSearchAsyncAction.java:512)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction$1.onFailure(AbstractSearchAsyncAction.java:349)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionListener$Delegating.onFailure(ActionListener.java:92)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionListenerResponseHandler.handleException(ActionListenerResponseHandler.java:48)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.SearchTransportService$ConnectionCountingHandler.handleException(SearchTransportService.java:642)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.transport.TransportService$UnregisterChildTransportResponseHandler.handleException(TransportService.java:1650)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler.handleException(TransportService.java:1390)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.transport.TransportService$DirectResponseChannel.processException(TransportService.java:1512)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.transport.TransportService$DirectResponseChannel.sendResponse(TransportService.java:1487)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.transport.TaskTransportChannel.sendResponse(TaskTransportChannel.java:50)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.support.ChannelActionListener.onFailure(ChannelActionListener.java:48)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionRunnable.onFailure(ActionRunnable.java:77)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:28)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:33)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:769)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)\n\tat java.base/java.lang.Thread.run(Thread.java:833)\nCaused by: org.elasticsearch.ElasticsearchException$1: Index: 43, Size: 1\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.ElasticsearchException.guessRootCauses(ElasticsearchException.java:638)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.search.AbstractSearchAsyncAction.executeNextPhase(AbstractSearchAsyncAction.java:416)\n\t... 20 more\nCaused by: java.lang.IndexOutOfBoundsException: Index: 43, Size: 1\n\tat java.base/java.util.Collections$SingletonList.get(Collections.java:4959)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.prepareNestedHitContext(FetchPhase.java:466)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.prepareHitContext(FetchPhase.java:312)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:165)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.execute(FetchPhase.java:93)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.subphase.InnerHitsPhase.hitExecute(InnerHitsPhase.java:76)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.subphase.InnerHitsPhase$1.process(InnerHitsPhase.java:52)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.buildSearchHits(FetchPhase.java:177)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.fetch.FetchPhase.execute(FetchPhase.java:93)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.executeFetchPhase(SearchService.java:659)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.executeQueryPhase(SearchService.java:634)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.search.SearchService.lambda$executeQueryPhase$2(SearchService.java:489)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionRunnable.lambda$supply$0(ActionRunnable.java:47)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.action.ActionRunnable$2.doRun(ActionRunnable.java:62)\n\tat org.elasticsearch.server@8.4.3/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)\n\t... 6 more\n"}`
server/src/test/java/org/elasticsearch/index/mapper/CopyToMapperTests.java
}
                                b.endArray();
                            }
                            b.endObject();
                        }
                        b.endObject();
                    }
                    b.endObject();
                }
                b.endObject();
            }
            b.endObject();
        }));
        ParsedDocument doc = mapper.parse(source(b -> {
            b.startArray("n1");
            {
                b.startObject();
                {
                    b.startArray("n2");
                    {
                        b.startObject().field("source", 3).endObject();
                        b.startObject().field("source", 5).endObject();
                    }
                    b.endArray();
                }
                b.endObject();
                b.startObject();
                {
                    b.startArray("n2");
                    {