### Description

`from employees | eval x = 1 | keep x` results in 

```
Caused by: java.lang.NullPointerException: Cannot invoke "java.lang.Integer.intValue()" because the return value of "org.elasticsearch.xpack.esql.planner.Layout.getChannel(org.elasticsearch.xpack.ql.expression.NameId)" is null
        at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.alignPageToAttributes(LocalExecutionPlanner.java:281)
        at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.planExchangeSink(LocalExecutionPlanner.java:305)
        at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:199)
        at org.elasticsearch.xpack.esql.planner.LocalExecutionPlanner.plan(LocalExecutionPlanner.java:146)
        at org.elasticsearch.xpack.esql.plugin.ComputeService.runCompute(ComputeService.java:246)
        at org.elasticsearch.xpack.esql.plugin.ComputeService$DataNodeRequestHandler.lambda$messageReceived$5(ComputeService.java:415)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.action.ActionListener$2.onResponse(ActionListener.java:177)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.action.ActionListener.completeWith(ActionListener.java:305)
        at org.elasticsearch.xpack.esql.plugin.ComputeService.lambda$acquireSearchContexts$13(ComputeService.java:280)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.index.shard.IndexShard.ensureShardSearchActive(IndexShard.java:3911)
        at org.elasticsearch.xpack.esql.plugin.ComputeService.acquireSearchContexts(ComputeService.java:278)
        at org.elasticsearch.xpack.esql.plugin.ComputeService$DataNodeRequestHandler.messageReceived(ComputeService.java:413)
        at org.elasticsearch.xpack.esql.plugin.ComputeService$DataNodeRequestHandler.messageReceived(ComputeService.java:405)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.transport.RequestHandlerRegistry.processMessageReceived(RequestHandlerRegistry.java:74)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.transport.TransportService$6.doRun(TransportService.java:1023)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:983)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:33)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:983)
        at org.elasticsearch.server@8.10.0-SNAPSHOT/org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
        at java.base/java.lang.Thread.run(Thread.java:1623)
```
x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionIT.java
public void testRowStatsProjectGroupByDouble() {
        EsqlQueryResponse results = run("row a = 1.0, b = 2 | stats count(b) by a | keep a");
        logger.info(results);
        assertThat(results.columns().stream().map(ColumnInfo::name).toList(), contains("a"));
        assertThat(results.columns().stream().map(ColumnInfo::type).toList(), contains("double"));
        assertThat(results.values(), contains(List.of(1.0)));
    }
    public void testRowStatsProjectGroupByKeyword() {
        EsqlQueryResponse results = run("row a = \"hello\", b = 2 | stats count(b) by a | keep a");
        logger.info(results);
        assertThat(results.columns().stream().map(ColumnInfo::name).toList(), contains("a"));
        assertThat(results.columns().stream().map(ColumnInfo::type).toList(), contains("keyword"));
        assertThat(results.values(), contains(List.of("hello")));
    }
    public void testFromStatsProjectGroupByDouble() {
        EsqlQueryResponse results = run("from test | stats count(count) by data_d | keep data_d");
        logger.info(results);
        assertThat(results.columns().stream().map(ColumnInfo::name).toList(), contains("data_d"));
        assertThat(results.columns().stream().map(ColumnInfo::type).toList(), contains("double"));
        assertThat(results.values(), containsInAnyOrder(List.of(1.0), List.of(2.0)));
    }
    public void testFromStatsProjectGroupWithAlias() {
        String query = "from test | stats avg_count = avg(count) by data | eval d2 = data | rename data as d | keep d, d2";
        EsqlQueryResponse results = run(query);
        logger.info(results);
        assertThat(results.columns().stream().map(ColumnInfo::name).toList(), contains("d", "d2"));
        assertThat(results.columns().stream().map(ColumnInfo::type).toList(), contains("long", "long"));
        assertThat(results.values(), containsInAnyOrder(List.of(1L, 1L), List.of(2L, 2L)));
    }
    public void testFromStatsProjectAgg() {