feat(ai-web): 修复出现遗留边的时候导致出现的null错误

service-ai/service-ai-web/src/main/java/com/lanyuanxiaoyao/service/ai/web/engine/FlowGraphRunner.java

@@ -1,5 +1,6 @@
 package com.lanyuanxiaoyao.service.ai.web.engine;
 
+import cn.hutool.core.util.ObjectUtil;
 import cn.hutool.core.util.StrUtil;
 import com.lanyuanxiaoyao.service.ai.web.engine.entity.FlowContext;
 import com.lanyuanxiaoyao.service.ai.web.engine.entity.FlowEdge;
@@ -47,6 +48,9 @@ public final class FlowGraphRunner {
     }
     while (!executionQueue.isEmpty()) {
       var node = executionQueue.poll();
+      if (ObjectUtil.isNull(node)) {
+        continue;
+      }
       process(node, flowContext);
     }
   }