### Description

A query like `from employees | where true` is perfectly valid. So is `from employees | where still_hired`. In other words, a simple boolean expression is accepted, even if that expression is a field. For fields `where [field_name]` is the short version of `where [field_name] == true`.

But, for fields that are not booleans `from employees | where salary` for example, ESQL throws an exception:

```
                "type": "class_cast_exception",
                "reason": "class org.elasticsearch.compute.data.IntVectorBlock cannot be cast to class org.elasticsearch.compute.data.BooleanBlock (org.elasticsearch.compute.data.IntVectorBlock and org.elasticsearch.compute.data.BooleanBlock are in unnamed module of loader java.net.FactoryURLClassLoader @c6a692e)"
```

The error message should be more user-friendly, like validating the parameters of regular functions.
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Verifier.java
}
                });
            } else if (p instanceof RegexExtract re) {
                Expression expr = re.input();
                DataType type = expr.dataType();
                if (EsqlDataTypes.isString(type) == false) {
                    failures.add(
                        fail(
                            expr,
                            "{} only supports KEYWORD or TEXT values, found expression [{}] type [{}]",
                            re.getClass().getSimpleName(),
                            expr.sourceText(),
                            type
                        )
                    );
                }
            } else if (p instanceof Row row) {
                failures.addAll(validateRow(row));
            } else if (p instanceof Eval eval) {
                failures.addAll(validateEval(eval));
            }
            p.forEachExpression(BinaryOperator.class, bo -> {
                Failure f = validateUnsignedLongOperator(bo);
                if (f != null) {
                    failures.add(f);
                }
            });
            p.forEachExpression(BinaryComparison.class, bc -> {
                Failure f = validateBinaryComparison(bc);
                if (f != null) {