```
ROW a="b c d"
| DISSECT a "%{b} %{} %{d}"
```
returns

```
       a       |       b       |               |       d       
---------------+---------------+---------------+---------------
b c d          |b              |null           |d 
```

it should ignore the empty pattern instead, and only return `a, b, d`
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/parser/StatementParserTests.java
}
    private static Literal literalUnsignedLongs(String... ulongs) {
        return new Literal(EMPTY, Arrays.stream(ulongs).map(s -> asLongUnsigned(new BigInteger(s))).toList(), DataTypes.UNSIGNED_LONG);
    }
    private static Literal literalBoolean(boolean b) {
        return new Literal(EMPTY, b, DataTypes.BOOLEAN);
    }
    private static Literal literalBooleans(boolean... booleans) {
        List<Boolean> v = new ArrayList<>(booleans.length);
        for (boolean b : booleans) {
            v.add(b);
        }
        return new Literal(EMPTY, v, DataTypes.BOOLEAN);
    }
    private static Literal literalString(String s) {
        return new Literal(EMPTY, s, DataTypes.KEYWORD);
    }
    private static Literal literalStrings(String... strings) {
        return new Literal(EMPTY, Arrays.asList(strings), DataTypes.KEYWORD);
    }
    private void expectError(String query, String errorMessage) {
        ParsingException e = expectThrows(ParsingException.class, "Expected syntax error for " + query, () -> statement(query));
        assertThat(e.getMessage(), containsString(errorMessage));
    }
    private void expectError(String query, List<TypedParamValue> params, String errorMessage) {
        ParsingException e = expectThrows(ParsingException.class, "Expected syntax error for " + query, () -> statement(query, params));
        assertThat(e.getMessage(), containsString(errorMessage));
    }
}