IDEA-261479 RecentProjectsFullScreenTabSupport: fix AIOOBE in headless mode

java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
	at com.intellij.ui.mac.MergeAllWindowsAction$RecentProjectsFullScreenTabSupport.appStarted(MergeAllWindowsAction.java:74)
	at com.intellij.util.messages.impl.MessageBusImplKt.invokeMethod(MessageBusImpl.kt:647)
	at com.intellij.util.messages.impl.MessageBusImplKt.invokeListener(MessageBusImpl.kt:630)
	at com.intellij.util.messages.impl.MessageBusImplKt.deliverMessage(MessageBusImpl.kt:400)
	at com.intellij.util.messages.impl.MessageBusImplKt.pumpWaiting(MessageBusImpl.kt:379)
	at com.intellij.util.messages.impl.MessageBusImplKt.access$pumpWaiting(MessageBusImpl.kt:1)
	at com.intellij.util.messages.impl.MessagePublisher.invoke(MessageBusImpl.kt:438)
	at jdk.proxy2/jdk.proxy2.$Proxy24.appStarted(Unknown Source)
	at fleet.backend.FleetStarter.main(FleetStarter.kt:85)
	at com.intellij.idea.ApplicationLoader$initApplication$4$1$1.run(ApplicationLoader.kt:183)
	at com.intellij.openapi.application.TransactionGuardImpl.performActivity(TransactionGuardImpl.java:106)
	at com.intellij.openapi.application.TransactionGuardImpl.performUserActivity(TransactionGuardImpl.java:95)
	at com.intellij.idea.ApplicationLoader$initApplication$4$1.run(ApplicationLoader.kt:182)
	at com.intellij.openapi.application.TransactionGuardImpl.runWithWritingAllowed(TransactionGuardImpl.java:215)
	at com.intellij.openapi.application.TransactionGuardImpl.access$100(TransactionGuardImpl.java:22)
	at com.intellij.openapi.application.TransactionGuardImpl$1.run(TransactionGuardImpl.java:197)
	at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:874)
	at com.intellij.openapi.application.impl.ApplicationImpl$3.run(ApplicationImpl.java:511)
	at com.intellij.openapi.application.impl.FlushQueue.doRun(FlushQueue.java:69)
	at com.intellij.openapi.application.impl.FlushQueue.runNextEvent(FlushQueue.java:112)
	at com.intellij.openapi.application.impl.FlushQueue.flushNow(FlushQueue.java:42)
	at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:777)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:728)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:747)
	at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:898)
	at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:746)
	at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$6(IdeEventQueue.java:439)
	at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:813)
	at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$7(IdeEventQueue.java:438)
	at com.intellij.openapi.application.TransactionGuardImpl.performActivity(TransactionGuardImpl.java:106)
	at com.intellij.ide.IdeEventQueue.performActivity(IdeEventQueue.java:604)
	at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$8(IdeEventQueue.java:436)
	at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:874)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:484)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

GitOrigin-RevId: 2fa6117fe6db1e63132fb3ab3c306e35594a8c92

platform/platform-impl/src/com/intellij/ui/mac/MergeAllWindowsAction.java

@@ -62,6 +62,10 @@ public class MergeAllWindowsAction extends DumbAwareAction {
     public void appStarted() {
       if (JdkEx.isTabbingModeAvailable()) {
         IdeFrame[] frames = WindowManager.getInstance().getAllProjectFrames();
+        if (frames.length == 0) {
+          return;
+        }
+
         if (frames.length > 1) {
           for (IdeFrame frame : frames) {
             if (!frame.isInFullScreen()) {