### 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
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */
package org.elasticsearch.xpack.esql.expression.function.scalar.math;
import org.elasticsearch.common.TriFunction;
import org.elasticsearch.compute.ann.Evaluator;
import org.elasticsearch.compute.operator.DriverContext;
import org.elasticsearch.compute.operator.EvalOperator.ExpressionEvaluator;
import org.elasticsearch.xpack.esql.EsqlIllegalArgumentException;
import org.elasticsearch.xpack.esql.evaluator.mapper.EvaluatorMapper;
import org.elasticsearch.xpack.ql.expression.Expression;
import org.elasticsearch.xpack.ql.expression.function.OptionalArgument;