How could valid be true while explanation has errors?

I'm running ES 7.17.10 and I have a simple index with the following mapping:

curl -XPUT -H 'Content-Type: application/json' 127.0.0.1:9200/test_index -d '{
    "settings": {
        "number_of_shards": 2,
        "number_of_replicas": 1
    },
    "mappings": {
        "properties": {
            "field1": { "type": "integer" },
            "field2": {
                "type": "nested",
                "properties": {
                    "nested1": { "type": "keyword" },
                    "nested2": { "type": "integer" }
                }
            }
        }
    }
}'

When I try to validate a query string, the valid part is true, but the explanation contains an error, is that normal?

# curl '127.0.0.1:9200/test_index/_validate/query?pretty&explain&q=field1:"test"'
{
  "_shards": {
    "total": 1,
    "successful": 1,
    "failed": 0
  },
  "valid": true,
  "explanations": [
    {
      "index": "test_index",
      "valid": true,
      "explanation": "MatchNoDocsQuery(\"failed [field1] query, caused by number_format_exception:[For input string: \"test\"]\")"
    }
  ]
}

validation: Validates a potentially expensive query without executing it.

explaination: Returns information about why a specific document matches (or doesn’t match) a query.

Your query is vaild, and the query result is empty set. And explaination info tells you why you get empty set because you query an integer field by a string param. And ES can handle the situation and will not throw an exception. I think ES is not strongly-type database engine.

{{es}}/vali/_search?pretty&q=field1:"test"

{
    "took": 2,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 0,
            "relation": "eq"
        },
        "max_score": null,
        "hits": []
    }
}

On the other hand, when you index wrong type data, ES will throw an exception.

{{es}}/vali/_doc

{
  "field1":aaa
}

{
    "error": {
        "root_cause": [
            {
                "type": "mapper_parsing_exception",
                "reason": "failed to parse field [field1] of type [integer] in document with id 'mjfPJ4gBNMihXAkDlss_'. Preview of field's value: 'aaa'"
            }
        ],
        "type": "mapper_parsing_exception",
        "reason": "failed to parse field [field1] of type [integer] in document with id 'mjfPJ4gBNMihXAkDlss_'. Preview of field's value: 'aaa'",
        "caused_by": {
            "type": "number_format_exception",
            "reason": "For input string: \"aaa\""
        }
    },
    "status": 400
}