### Elasticsearch Version

main@b6747b48ba0901a530ba51375e3576fdb8df8527

### Installed Plugins

_No response_

### Java Version

openjdk version "17.0.8" 2023-07-18

### OS Version

Ubuntu 23.04

### Problem Description

`row a = 1 | stats max(1) by a` (or some other agg) results in:
```
Caused by: java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at java.base/java.util.ImmutableCollections$List12.<init>(ImmutableCollections.java:556)
	at java.base/java.util.List.of(List.java:812)
	at org.elasticsearch.xpack.esql.planner.AbstractPhysicalOperationProviders.aggregatesToFactory(AbstractPhysicalOperationProviders.java:185)
	at org.elasticsearch.xpack.esql.planner.AbstractPhysicalOperationProviders.groupingPhysicalOperation(AbstractPhysicalOperationProviders.java:133)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.planAggregation(LocalExecutionPlanner.java:207)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:158)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.planAggregation(LocalExecutionPlanner.java:207)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:158)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.planLimit(LocalExecutionPlanner.java:520)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:176)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.planOutput(LocalExecutionPlanner.java:259)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:198)
	at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:147)
	at org.elasticsearch.xpack.esql.plugin.ComputeService.runCompute(ComputeService.java:204)
	... 147 more
```

@nik9000 's thoughts on this: `I think this is just a kind of special case of "I can't EVAL in STATS". But it's a case the parser accepts.`

### Steps to Reproduce

Run the ESQL query from above.

### Logs (if relevant)

_No response_
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/VerifierTests.java
public void testMixedNonConvertibleTypesInIn() {
        assertEquals(
            "1:19: 2nd argument of [emp_no in (1, \"two\")] must be [integer], found value [\"two\"] type [keyword]",
            error("from test | where emp_no in (1, \"two\")")
        );
    }
    public void testMixedNumericalNonConvertibleTypesInIn() {
        assertEquals(
            "1:19: 2nd argument of [3 in (1, to_ul(3))] must be [integer], found value [to_ul(3)] type [unsigned_long]",
            error("from test | where 3 in (1, to_ul(3))")
        );
        assertEquals(
            "1:19: 1st argument of [to_ul(3) in (1, 3)] must be [unsigned_long], found value [1] type [integer]",
            error("from test | where to_ul(3) in (1, 3)")
        );
    }
    public void testUnsignedLongTypeMixInComparisons() {
        List<String> types = EsqlDataTypes.types()
            .stream()
            .filter(dt -> dt.isNumeric() && EsqlDataTypes.isRepresentable(dt) && dt != UNSIGNED_LONG)
            .map(DataType::typeName)
            .toList();
        for (var type : types) {
            for (var comp : List.of("==", "!=", ">", ">=", "<=", "<")) {
                String left, right, leftType, rightType;
                if (randomBoolean()) {
                    left = "ul";
                    leftType = "unsigned_long";
                    right = "n";
                    rightType = type;