TASK: Improve import error if workspace contains events or does not e…

…xist at all and projections were stale

Neos.ContentRepository.Export/src/Processors/EventStoreImportProcessor.php

@@ -100,7 +100,7 @@ public function run(ProcessingContext $context): void
         try {
             $this->eventStore->commit($contentStreamStreamName, Events::fromArray($domainEvents), ExpectedVersion::fromVersion(Version::first()));
         } catch (ConcurrencyException $e) {
-            throw new \RuntimeException(sprintf('Failed to publish %d events because the event stream "%s" for workspace "%s" already contains events.', count($domainEvents), $contentStreamStreamName->value, $workspace->workspaceName->value), 1729506818, $e);
+            throw new \RuntimeException(sprintf('Failed to publish %d events because the event stream "%s" for workspace "%s". Please prune the content repository first via `./flow site:pruneAll`.', count($domainEvents), $contentStreamStreamName->value, $workspace->workspaceName->value), 1729506818, $e);
         }
     }
 }