### 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
public RoundTests(@Name("TestCase") Supplier<TestCaseSupplier.TestCase> testCaseSupplier) {
        this.testCase = testCaseSupplier.get();
    }
    @ParametersFactory
    public static Iterable<Object[]> parameters() {
        return parameterSuppliersFromTypedData(List.of(new TestCaseSupplier("round(<double>, <int>)", () -> {
            double number = 1 / randomDouble();
            int precision = between(-30, 30);
            return new TestCaseSupplier.TestCase(
                List.of(
                    new TestCaseSupplier.TypedData(number, DataTypes.DOUBLE, "number"),
                    new TestCaseSupplier.TypedData(precision, DataTypes.INTEGER, "precision")
                ),