Fix when using Empty BaseResult which has m_sess = NULL (Bug #25515964 )

Author: silvakid

devapi/result.cc

@@ -1345,10 +1345,14 @@ void mysqlx::internal::BaseResult::init(mysqlx::internal::BaseResult &&init_)
 
   m_sess = init_.m_sess;
 
-  // first deregister init result, since it registered itself on ctor
-  // otherwise it would trigger cache, and we are moving Result object
-  m_sess->deregister_result(&init_);
-  m_sess->register_result(this);
+  //On empty results, m_sess is NULL, so don't do anything with it!
+  if (m_sess)
+  {
+    // first deregister init result, since it registered itself on ctor
+    // otherwise it would trigger cache, and we are moving Result object
+    m_sess->deregister_result(&init_);
+    m_sess->register_result(this);
+  }
 
 }
 

devapi/tests/crud-t.cc

@@ -848,6 +848,13 @@ TEST_F(Crud, table)
 
   std::vector<string> cols = {"_id"};
 
+  //Inserting empty list
+
+  //Bug #25515964
+  //Adding empty list shouldn't do anything
+  std::list<Row> rList;
+  tbl.insert(cols, "age", string("name")).rows(rList).rows(rList).execute();
+
   //Using containers (vectors, const char* and string)
 
   auto insert = tbl.insert(cols, "age", string("name"));