NullPointerException because "this.launcherFuture" is null

[basilevs]

Following exception happens on shutdown (very rarely).

!ENTRY org.eclipse.lsp4e 4 0 2023-06-07 23:46:45.902
!MESSAGE java.lang.NullPointerException: Cannot invoke "java.util.concurrent.Future.isCancelled()" because "this.launcherFuture" is null
!STACK 0
java.util.concurrent.ExecutionException: java.lang.NullPointerException: Cannot invoke "java.util.concurrent.Future.isCancelled()" because "this.launcherFuture" is null
	at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:396)
	at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2096)
	at org.eclipse.lsp4e.LanguageServerWrapper.lambda$9(LanguageServerWrapper.java:479)
	at java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1804)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Cannot invoke "java.util.concurrent.Future.isCancelled()" because "this.launcherFuture" is null
	at org.eclipse.lsp4e.LanguageServerWrapper.isActive(LanguageServerWrapper.java:417)
	at org.eclipse.lsp4e.LanguageServerWrapper.lambda$5(LanguageServerWrapper.java:322)
	at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.request(RemoteEndpoint.java:161)
	at org.eclipse.lsp4j.jsonrpc.services.EndpointProxy.invoke(EndpointProxy.java:91)
	at jdk.proxy10/jdk.proxy10.$Proxy32.shutdown(Unknown Source)
	at org.eclipse.lsp4e.LanguageServerWrapper.lambda$9(LanguageServerWrapper.java:477)
	... 4 more

The reason seems to be the lack of synchronization resulting in a change of a prechecked non-null value in the middle of expression computation.