### 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/test/java/org/elasticsearch/xpack/esql/optimizer/PhysicalPlanOptimizerTests.java
assertThat(metadataAttribute.name(), is("_index"));
            extract = as(filter.child(), FieldExtractExec.class);
            var source = source(extract.child());
        }
    }
    public void testDontPushDownMetadataVersionAndId() {
        for (var t : List.of(tuple("_version", "2"), tuple("_id", "\"2\""))) {
            var plan = physicalPlan("from test [metadata " + t.v1() + "] | where " + t.v1() + " == " + t.v2());
            var optimized = optimizedPlan(plan);
            var limit = as(optimized, LimitExec.class);
            var exchange = asRemoteExchange(limit.child());
            var project = as(exchange.child(), ProjectExec.class);
            var extract = as(project.child(), FieldExtractExec.class);
            limit = as(extract.child(), LimitExec.class);
            var filter = as(limit.child(), FilterExec.class);
            assertThat(filter.condition(), instanceOf(Equals.class));
            assertThat(((Equals) filter.condition()).left(), instanceOf(MetadataAttribute.class));
            var metadataAttribute = (MetadataAttribute) ((Equals) filter.condition()).left();
            assertThat(metadataAttribute.name(), is(t.v1()));
            extract = as(filter.child(), FieldExtractExec.class);
            var source = source(extract.child());
        }
    }
    private static EsQueryExec source(PhysicalPlan plan) {
        if (plan instanceof ExchangeExec exchange) {
            plan = exchange.child();
        }
        return as(plan, EsQueryExec.class);
    }
    private PhysicalPlan optimizedPlan(PhysicalPlan plan) {