Check current_execute_data instead of flags in fiber destructor

Checking EG(current_exectue_data) throws into the previous fiber instead of triggering a fatal error during shutdown. A fatal error is triggered only if the throwing destroyed fiber was resumed from {main}.

Zend/tests/fibers/throw-in-multiple-destroyed-fibers-after-shutdown.phpt

@@ -0,0 +1,47 @@
+--TEST--
+Throw in multiple destroyed fibers after shutdown
+--FILE--
+<?php
+
+$fiber = new Fiber(function (): void {
+    $fiber1 = new Fiber(function (): void {
+        try {
+            Fiber::suspend();
+        } finally {
+            throw new Exception('test1');
+        }
+    });
+
+    $fiber1->start();
+
+    $fiber2 = new Fiber(function (): void {
+        try {
+            Fiber::suspend();
+        } finally {
+            throw new Exception('test2');
+        }
+    });
+
+    $fiber2->start();
+
+    Fiber::suspend();
+});
+
+$fiber->start();
+
+echo "done\n";
+
+?>
+--EXPECTF--
+done
+
+Fatal error: Uncaught Exception: test1 in %sthrow-in-multiple-destroyed-fibers-after-shutdown.php:%d
+Stack trace:
+#0 [internal function]: {closure}()
+#1 {main}
+
+Next Exception: test2 in %sthrow-in-multiple-destroyed-fibers-after-shutdown.php:%d
+Stack trace:
+#0 [internal function]: {closure}()
+#1 {main}
+  thrown in %sthrow-in-multiple-destroyed-fibers-after-shutdown.php on line %d

Zend/zend_fibers.c

@@ -405,7 +405,7 @@ static void zend_fiber_object_destroy(zend_object *object)
 
 		zend_exception_set_previous(EG(exception), exception);
 
-		if (EG(flags) & EG_FLAGS_IN_SHUTDOWN) {
+		if (!EG(current_execute_data)) {
 			zend_exception_error(EG(exception), E_ERROR);
 		}
 	} else {