### Elasticsearch Version

8.11.0

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

MacOS

### Problem Description

When sending a ESQL query with the `enrich` command that involves a policy that does not existing a `NullPointerException` is thrown and shown as error messages to the user:

Query:
```
row a  = 1| enrich missing-policy
```

Returns:
```
null_pointer_exception - Cannot invoke "org.elasticsearch.xpack.core.enrich.EnrichPolicy.getMatchField()" because "policy" is null
```

### Steps to Reproduce

See above.

### Logs (if relevant)

_No response_
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/AnalyzerTests.java
| where length(unsupported) > 0
            """, errorMessage);
    }
    public void testUnsupportedFieldSortAfterProject() {
        var errorMessage = "Cannot use field [unsupported] with unsupported type [ip_range]";
        verifyUnsupported("""
            from test
            | keep unsupported
            | sort unsupported
            """, errorMessage);
    }
    public void testIncludeUnsupportedFieldPattern() {
        var e = expectThrows(VerificationException.class, () -> analyze("""
            from test
            | keep un*
            """));
        assertThat(e.getMessage(), containsString("No match found for [un*]"));
    }
    public void testDropUnsupportedFieldExplicit() {
        assertProjectionWithMapping(
            """
                from test
                | drop unsupported
                """,
            "mapping-multi-field-variation.json",
            "bool",
            "date",
            "date_nanos",
            "float",
            "foo_type",