### 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 testUnsignedLongNegation() {
        assertEquals(
            "1:29: negation unsupported for arguments of type [unsigned_long] in expression [-x]",
            error("row x = to_ul(1) | eval y = -x")
        );
    }
    public void testSumOnDate() {
        assertEquals(
            "1:19: argument of [sum(hire_date)] must be [numeric], found value [hire_date] type [datetime]",
            error("from test | stats sum(hire_date)")
        );
    }
    public void testWrongInputParam() {
        assertEquals(
            "1:19: first argument of [emp_no == ?] is [numeric] so second argument must also be [numeric] but was [keyword]",
            error("from test | where emp_no == ?", "foo")
        );
        assertEquals(
            "1:19: first argument of [emp_no == ?] is [numeric] so second argument must also be [numeric] but was [null]",
            error("from test | where emp_no == ?", new Object[] { null })
        );
    }
    public void testPeriodAndDurationInRowAssignment() {
        for (var unit : List.of("millisecond", "second", "minute", "hour", "day", "week", "month", "year")) {
            assertEquals("1:5: cannot use [1 " + unit + "] directly in a row assignment", error("row a = 1 " + unit));
        }
    }
    public void testSubtractDateTimeFromTemporal() {
        for (var unit : List.of("millisecond", "second", "minute", "hour")) {
            assertEquals(