Question about Ignore_malformed option on Derived field

OpenSearch
1

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
OpenSearch 2.15

Describe the issue:

A Boolean value that specifies whether to ignore malformed values when running a query on a derived field.

From the derived field document

Does this mean the ignore_malfomed only support query?
How about fields parameter in the search request?
It would be great to ignore the error for fetching derived field to search response too, I think.

Reproduce example requests.

### 
DELETE /derived-sample-logs

### create index
PUT /derived-sample-logs
{
  "mappings": {
    "properties": {
      "request": {
        "type": "text",
        "fields": {
          "keyword": {
            "type": "keyword"
          }
        }
      },
      "clientip": {
        "type": "keyword"
      }
    }
  }
}

### PUT the derived fields
PUT /derived-sample-logs/_mapping
{
  "derived": {
    "timestamp": {
      "type": "date",
      "format": "MM/dd/yyyy HH:mm:ss",
      "script": {
        "source": "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[0]))"
      }
    },
    "method": {
      "type": "keyword",
      "script": {
        "source": "emit(doc[\"request.keyword\"].value.splitOnToken(\" \")[1])"
      }
    },
    "size": {
      "type": "long",
      "script": {
        "source": "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[5]))"
      }
    }
  }
}

### index an error data
PUT /derived-sample-logs/_doc/7
{ 
  "request": "hoge GET /english/images/france98_venues.gif HTTP/1.0 200 778", 
  "clientip": "61.177.2.0" 
}

### match_all search with fields param
GET /derived-sample-logs/_search
{
  "fields": ["request", "clientip", "timestamp"]
}

The error from OpenSearch.

{
  "error": {
    "root_cause": [
      {
        "type": "script_exception",
        "reason": "runtime error",
        "script_stack": [
          "java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)",
          "java.base/java.lang.Long.parseLong(Long.java:709)",
          "java.base/java.lang.Long.parseLong(Long.java:832)",
          "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[0]))",
          "                                                                  ^---- HERE"
        ],
        "script": "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[0]))",
        "lang": "painless",
        "position": {
          "offset": 66,
          "start": 0,
          "end": 71
        }
      }
    ],
    "type": "search_phase_execution_exception",
    "reason": "all shards failed",
    "phase": "query",
    "grouped": true,
    "failed_shards": [
      {
        "shard": 0,
        "index": "derived-sample-logs",
        "node": "kcP6GWKmR_6oA1IGf3d4fw",
        "reason": {
          "type": "script_exception",
          "reason": "runtime error",
          "script_stack": [
            "java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)",
            "java.base/java.lang.Long.parseLong(Long.java:709)",
            "java.base/java.lang.Long.parseLong(Long.java:832)",
            "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[0]))",
            "                                                                  ^---- HERE"
          ],
          "script": "emit(Long.parseLong(doc[\"request.keyword\"].value.splitOnToken(\" \")[0]))",
          "lang": "painless",
          "position": {
            "offset": 66,
            "start": 0,
            "end": 71
          },
          "caused_by": {
            "type": "number_format_exception",
            "reason": "For input string: \"hoge\""
          }
        }
      }
    ]
  },
  "status": 400
}