Merge pull request quarkusio#42208 from Sanne/ShutdownRace

Avoid a possible NPE during application stop

core/runtime/src/main/java/io/quarkus/runtime/ApplicationLifecycleManager.java

@@ -429,13 +429,15 @@ public void run() {
             } finally {
                 stateLock.unlock();
             }
-            if (currentApplication.isStarted()) {
+            //take a reliable reference before changing the application state:
+            final Application app = currentApplication;
+            if (app.isStarted()) {
                 // On CLI apps, SIGINT won't call io.quarkus.runtime.Application#stop(),
                 // making the awaitShutdown() below block the application termination process
                 // It should be a noop if called twice anyway
-                currentApplication.stop();
+                app.stop();
             }
-            currentApplication.awaitShutdown();
+            app.awaitShutdown();
             currentApplication = null;
             System.out.flush();
             System.err.flush();