Prevent document unloading if active connections exist

This change ensures that a document is not unloaded while it still has active connections. It adds a condition to check the connection count before proceeding with the unload process. This prevents potential disruptions for connected clients.

packages/server/src/Hocuspocus.ts

@@ -592,6 +592,10 @@ export class Hocuspocus {
 
     await this.hooks('beforeUnloadDocument', { instance: this, documentName })
 
+    if (document.getConnectionsCount() > 0) {
+      return
+    }
+
     this.documents.delete(documentName)
     document.destroy()
     await this.hooks('afterUnloadDocument', { instance: this, documentName })