```
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
Grok dissect = (Grok) cmd;
        assertEquals("%{WORD:foo}", dissect.parser().pattern());
        assertEquals(List.of(referenceAttribute("foo", KEYWORD)), dissect.extractedFields());
        ParsingException pe = expectThrows(ParsingException.class, () -> statement("row a = \"foo bar\" | grok a \"%{_invalid_:x}\""));
        assertThat(
            pe.getMessage(),
            containsString("Invalid pattern [%{_invalid_:x}] for grok: Unable to find pattern [_invalid_] in Grok's pattern dictionary")
        );
    }
    public void testLikeRLike() {
        LogicalPlan cmd = processingCommand("where foo like \"*bar*\"");
        assertEquals(Filter.class, cmd.getClass());
        Filter filter = (Filter) cmd;
        assertEquals(WildcardLike.class, filter.condition().getClass());
        WildcardLike like = (WildcardLike) filter.condition();
        assertEquals("*bar*", like.pattern().pattern());
        cmd = processingCommand("where foo rlike \".*bar.*\"");
        assertEquals(Filter.class, cmd.getClass());
        filter = (Filter) cmd;
        assertEquals(RLike.class, filter.condition().getClass());
        RLike rlike = (RLike) filter.condition();
        assertEquals(".*bar.*", rlike.pattern().asJavaRegex());
        expectError("from a | where foo like 12", "mismatched input '12'");
        expectError("from a | where foo rlike 12", "mismatched input '12'");
    }
    public void testEnrich() {
        assertEquals(
            new Enrich(EMPTY, PROCESSING_CMD_INPUT, new Literal(EMPTY, "countries", KEYWORD), new EmptyAttribute(EMPTY), null, List.of()),
            processingCommand("enrich countries")
        );