### 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/test/java/org/elasticsearch/xpack/esql/analysis/VerifierTests.java
return error(query, defaultAnalyzer);
    }
    private String error(String query, Object... params) {
        return error(query, defaultAnalyzer, params);
    }
    private String error(String query, Analyzer analyzer, Object... params) {
        List<TypedParamValue> parameters = new ArrayList<>();
        for (Object param : params) {
            if (param == null) {
                parameters.add(new TypedParamValue("null", null));
            } else if (param instanceof String) {
                parameters.add(new TypedParamValue("keyword", param));
            } else if (param instanceof Number) {
                parameters.add(new TypedParamValue("param", param));
            } else {
                throw new IllegalArgumentException("VerifierTests don't support params of type " + param.getClass());
            }
        }
        VerificationException e = expectThrows(
            VerificationException.class,
            () -> analyzer.analyze(parser.createStatement(query, parameters))
        );
        String message = e.getMessage();
        assertTrue(message.startsWith("Found "));
        String pattern = "\nline ";
        int index = message.indexOf(pattern);
        return message.substring(index + pattern.length());
    }
}