### 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
assertEquals(-123.5, process(-123.45, 1));
        assertEquals(-124.0, process(-123.5, 0));
        assertEquals(-123.0, process(-123.45));
        assertEquals(123.456, process(123.456, Integer.MAX_VALUE));
        assertEquals(0.0, process(123.456, Integer.MIN_VALUE));
        assertEquals(0L, process(0L, 0));
        assertEquals(0, process(0, 0));
        assertEquals(Long.MAX_VALUE, process(Long.MAX_VALUE));
        assertEquals(Long.MAX_VALUE, process(Long.MAX_VALUE, 5));
        assertEquals(Long.MIN_VALUE, process(Long.MIN_VALUE));
        assertEquals(Long.MIN_VALUE, process(Long.MIN_VALUE, 5));
    }
    private Object process(Number val) {
        try (
            Block.Ref ref = evaluator(new Round(Source.EMPTY, field("val", typeOf(val)), null)).get(driverContext()).eval(row(List.of(val)))
        ) {
            return toJavaObject(ref.block(), 0);
        }
    }
    private Object process(Number val, int decimals) {
        try (
            Block.Ref ref = evaluator(new Round(Source.EMPTY, field("val", typeOf(val)), field("decimals", DataTypes.INTEGER))).get(
                driverContext()
            ).eval(row(List.of(val, decimals)))
        ) {
            return toJavaObject(ref.block(), 0);
        }
    }
    private DataType typeOf(Number val) {
        if (val instanceof Integer) {