Return error on failed shrink

src/kv_db.cpp

@@ -197,6 +197,7 @@ struct kv_op_t
 
     void exec();
     void next(); // for list
+    ~kv_op_t();
 protected:
     int recheck_policy = KV_RECHECK_LEAF;
     bool started = false;
@@ -985,6 +986,15 @@ void kv_op_t::exec()
         finish(-ENOSYS);
 }
 
+kv_op_t::~kv_op_t()
+{
+    if (started && !done)
+    {
+        done = true;
+        db->active_ops--;
+    }
+}
+
 void kv_op_t::finish(int res)
 {
     auto db = this->db;
@@ -2040,10 +2050,5 @@ void kv_dbw_t::list_next(void *handle, std::function<void(int res, const std::st
 void kv_dbw_t::list_close(void *handle)
 {
     kv_op_t *op = (kv_op_t*)handle;
-    if (op->started && !op->done)
-    {
-        op->done = true;
-        op->db->active_ops--;
-    }
     delete op;
 }