```
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
assertThat(alias.child().fold(), is(Period.ofDays(2)));
        field = row.fields().get(3);
        assertThat(field.name(), is("b"));
        assertThat(field, instanceOf(Alias.class));
        alias = (Alias) field;
        assertThat(alias.child().fold(), is(Duration.ofHours(4)));
        field = row.fields().get(4);
        assertThat(field.name(), is("c"));
        assertThat(field, instanceOf(Alias.class));
        alias = (Alias) field;
        assertThat(alias.child().fold().getClass(), is(Version.class));
        assertThat(alias.child().fold().toString(), is("1.2.3"));
    }
    public void testWrongIntervalParams() {
        expectError("row x = ?", List.of(new TypedParamValue("date_period", "12")), "Cannot parse [12] to DATE_PERIOD");
        expectError("row x = ?", List.of(new TypedParamValue("time_duration", "12")), "Cannot parse [12] to TIME_DURATION");
        expectError(
            "row x = ?",
            List.of(new TypedParamValue("date_period", "12 months foo")),
            "Cannot parse [12 months foo] to DATE_PERIOD"
        );
        expectError(
            "row x = ?",
            List.of(new TypedParamValue("time_duration", "12 minutes bar")),
            "Cannot parse [12 minutes bar] to TIME_DURATION"
        );
        expectError("row x = ?", List.of(new TypedParamValue("date_period", "12 foo")), "Unexpected time interval qualifier: 'foo'");
        expectError("row x = ?", List.of(new TypedParamValue("time_duration", "12 bar")), "Unexpected time interval qualifier: 'bar'");
        expectError("row x = ?", List.of(new TypedParamValue("date_period", "foo days")), "Cannot parse [foo days] to DATE_PERIOD");
        expectError(