### Elasticsearch Version

8.11.0

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

MacOS

### Problem Description

The following ESQL statement reports and unhandled error:

```
from index | eval round([1.2])
```

Returns the rror:
```
class_cast_exception - class java.util.ImmutableCollections$ListN cannot be cast to class java.lang.Number (java.util.ImmutableCollections$ListN and java.lang.Number are in module java.base of loader 'bootstrap')
```

### Steps to Reproduce

See above

### Logs (if relevant)

_No response_
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/math/RoundTests.java
return DataTypes.INTEGER;
        }
        if (val instanceof Long) {
            return DataTypes.LONG;
        }
        if (val instanceof Double) {
            return DataTypes.DOUBLE;
        }
        throw new UnsupportedOperationException("unsupported type [" + val.getClass() + "]");
    }
    @Override
    protected DataType expectedType(List<DataType> argTypes) {
        return argTypes.get(0);
    }
    public void testNoDecimalsToString() {
        assertThat(
            evaluator(new Round(Source.EMPTY, field("val", DataTypes.DOUBLE), null)).get(driverContext()).toString(),
            equalTo("RoundDoubleNoDecimalsEvaluator[val=Attribute[channel=0]]")
        );
    }
    @Override
    protected List<ArgumentSpec> argSpec() {
        return List.of(required(numerics()), optional(integers()));
    }
    @Override
    protected Expression build(Source source, List<Expression> args) {
        return new Round(source, args.get(0), args.size() < 2 ? null : args.get(1));
    }
}