Fix px join filter core in assign parameter

src/sql/engine/px/ob_px_bloom_filter.cpp

@@ -551,7 +551,6 @@ int ObSendBloomFilterP::process_px_bloom_filter_data()
         phase_end))) {
       LOG_WARN("fail to process recieve count", K(ret));
     }
-    (void)filter->dec_merge_filter_count();
   }
 
   if (OB_SUCC(ret) && phase_end && arg_.is_first_phase() && !arg_.next_peer_addrs_.empty()) {
@@ -584,6 +583,9 @@ int ObSendBloomFilterP::process_px_bloom_filter_data()
       }
     }
   }
+  if (OB_NOT_NULL(filter)) {
+    (void)filter->dec_merge_filter_count();
+  }
   return ret;
 }