### 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
}
    public void testRenameUnsupportedField() {
        assertProjectionWithMapping("""
            from test
            | rename unsupported as u
            | keep int, u, float
            """, "mapping-multi-field-variation.json", "int", "u", "float");
    }
    public void testRenameUnsupportedFieldChained() {
        assertProjectionWithMapping("""
            from test
            | rename unsupported as u1, u1 as u2
            | keep int, u2, float
            """, "mapping-multi-field-variation.json", "int", "u2", "float");
    }
    public void testRenameUnsupportedAndResolved() {
        assertProjectionWithMapping("""
            from test
            | rename unsupported as u, float as f
            | keep int, u, f
            """, "mapping-multi-field-variation.json", "int", "u", "f");
    }
    public void testRenameUnsupportedSubFieldAndResolved() {
        assertProjectionWithMapping("""
            from test
            | rename some.string as ss, float as f
            | keep int, ss, f
            """, "mapping-multi-field-variation.json", "int", "ss", "f");
    }
    public void testRenameUnsupportedAndUnknown() {