fix: improve span handling in AsyncQueueJobMessageAspect to prevent null reference

Author: huangdijia

src/Tracing/Aspect/AsyncQueueJobMessageAspect.php

@@ -94,15 +94,16 @@ public function handlePush(ProceedingJoinPoint $proceedingJoinPoint)
 
         return trace(
             function (Scope $scope) use ($proceedingJoinPoint, $messageId, $destinationName, $bodySize) {
-                $span = $scope->getSpan();
-                $carrier = Carrier::fromSpan($span)->with([
-                    'publish_time' => microtime(true),
-                    'message_id' => $messageId,
-                    'destination_name' => $destinationName,
-                    'body_size' => $bodySize,
-                ]);
-
-                Context::set(Constants::TRACE_CARRIER, $carrier);
+                if ($span = $scope->getSpan()) {
+                    $carrier = Carrier::fromSpan($span)->with([
+                        'publish_time' => microtime(true),
+                        'message_id' => $messageId,
+                        'destination_name' => $destinationName,
+                        'body_size' => $bodySize,
+                    ]);
+
+                    Context::set(Constants::TRACE_CARRIER, $carrier);
+                }
 
                 return $proceedingJoinPoint->process();
             },