Optimize query uniqueness check in ProcessList - move after `cancelle…

…d_cv.wait`

src/Interpreters/ProcessList.cpp

@@ -311,12 +311,12 @@ ProcessListEntry::~ProcessListEntry()
         }
     }
 
-    if (auto query_user = parent.queries_to_user.find(query_id); query_user != parent.queries_to_user.end())
-        parent.queries_to_user.erase(query_user);
-
     /// Wait for the query if it is in the cancellation right now.
     parent.cancelled_cv.wait(lock.lock, [&]() { return process_list_element_ptr->is_cancelling == false; });
 
+    if (auto query_user = parent.queries_to_user.find(query_id); query_user != parent.queries_to_user.end())
+        parent.queries_to_user.erase(query_user);
+
     /// This removes the memory_tracker of one request.
     parent.processes.erase(it);