### 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/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/math/Round.java
static int process(int val, long decimals) {
        return Maths.round(val, decimals).intValue();
    }
    @Evaluator(extraName = "Long")
    static long process(long val, long decimals) {
        return Maths.round(val, decimals).longValue();
    }
    @Evaluator(extraName = "UnsignedLong")
    static long processUnsignedLong(long val, long decimals) {
        Number ul = unsignedLongAsNumber(val);
        if (ul instanceof BigInteger bi) {
            BigInteger rounded = Maths.round(bi, decimals);
            BigInteger unsignedLong = asUnsignedLong(rounded);
            return asLongUnsigned(unsignedLong);
        } else {
            return asLongUnsigned(Maths.round(ul.longValue(), decimals));
        }
    }
    @Evaluator(extraName = "Double")
    static double process(double val, long decimals) {
        return Maths.round(val, decimals).doubleValue();
    }
    @Override
    public final Expression replaceChildren(List<Expression> newChildren) {
        return new Round(source(), newChildren.get(0), decimals() == null ? null : newChildren.get(1));
    }
    @Override
    protected NodeInfo<? extends Expression> info() {
        return NodeInfo.create(this, Round::new, field(), decimals());
    }