### 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
| keep first*name
            """, "first_name");
        assertProjectionTypes("""
            from test
            | keep first*name
            """, DataTypes.KEYWORD);
    }
    public void testProjectIncludePattern() {
        assertProjection("""
            from test
            | keep *name
            """, "first_name", "last_name");
    }
    public void testProjectIncludeMultiStarPattern() {
        assertProjection("""
            from test
            | keep *t*name
            """, "first_name", "last_name");
    }
    public void testProjectStar() {
        assertProjection("""
            from test
            | keep *
            """, "_meta_field", "emp_no", "first_name", "gender", "job", "job.raw", "languages", "last_name", "long_noidx", "salary");
    }
    public void testNoProjection() {
        assertProjection("""
            from test
            """, "_meta_field", "emp_no", "first_name", "gender", "job", "job.raw", "languages", "last_name", "long_noidx", "salary");
        assertProjectionTypes(