fix an issue that node sockets can be duplicated

common/util_algorithm.hh

@@ -7,14 +7,17 @@
 namespace nf7::util {
 
 template <typename T>
-inline void Uniq(std::vector<T>& v) noexcept {
+inline size_t Uniq(std::vector<T>& v) noexcept {
+  size_t n = 0;
   for (auto itr = v.begin(); itr < v.end();) {
     if (v.end() != std::find(itr+1, v.end(), *itr)) {
       itr = v.erase(itr);
+      ++n;
     } else {
       ++itr;
     }
   }
+  return n;
 }
 
 }  // namespace nf7::util