Do not give CodeActions for stale diagnostics

[rgrunber]

Signed-off-by: Roland Grunberg rgrunber@redhat.com

See eclipse/lsp4mp#273 . It turns out we have the same issue in Qute templates. As @angelozerr mentions, if you have a template like :

{#for item in items}
{/for}

and change items quickly, it can occur.

[Error - 2:59:06 p.m.] Request textDocument/codeAction failed.
  Message: Internal error.
  Code: -32603 
java.util.concurrent.CompletionException: java.lang.ClassCastException: class com.redhat.qute.parser.template.sections.ForSection cannot be cast to class com.redhat.qute.parser.expression.ObjectPart (com.redhat.qute.parser.template.sections.ForSection and com.redhat.qute.parser.expression.ObjectPart are in unnamed module of loader 'app')
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.scan(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)
Caused by: java.lang.ClassCastException: class com.redhat.qute.parser.template.sections.ForSection cannot be cast to class com.redhat.qute.parser.expression.ObjectPart (com.redhat.qute.parser.template.sections.ForSection and com.redhat.qute.parser.expression.ObjectPart are in unnamed module of loader 'app')
	at com.redhat.qute.services.codeactions.QuteCodeActionForUndefinedObject.doCodeActions(QuteCodeActionForUndefinedObject.java:77)
	at com.redhat.qute.services.QuteCodeActions.doCodeActions(QuteCodeActions.java:98)
	at com.redhat.qute.services.QuteLanguageService.doCodeActions(QuteLanguageService.java:101)
	at com.redhat.qute.ls.template.TemplateFileTextDocumentService.lambda$codeAction$9(TemplateFileTextDocumentService.java:161)
	at com.redhat.qute.ls.commons.ModelTextDocuments.lambda$computeModelAsyncCompose$1(ModelTextDocuments.java:144)
	... 7 more

[angelozerr]

It works like a charm, thanks @rgrunber !