Try move num_son init from do_apply

libraries/chain/account_evaluator.cpp

@@ -191,11 +191,6 @@ object_id_type account_create_evaluator::do_apply( const account_create_operatio
       obj.active           = o.active;
       obj.options          = o.options;
 
-      if (!obj.options.extensions.value.num_son.valid())
-      {
-         obj.options.extensions.value = account_options::ext();
-      }
-
       obj.statistics = d.create<account_statistics_object>([&obj](account_statistics_object& s){
                            s.owner = obj.id;
                            s.name = obj.name;
@@ -335,6 +330,7 @@ void_result account_update_evaluator::do_apply( const account_update_operation&
          a.top_n_control_flags = 0;
       }
       if( o.new_options ) a.options = *o.new_options;
+
       if( o.extensions.value.owner_special_authority.valid() )
       {
          a.owner_special_authority = *(o.extensions.value.owner_special_authority);

libraries/chain/db_maint.cpp

@@ -2382,7 +2382,24 @@ void database::perform_chain_maintenance(const signed_block& next_block, const g
 
             if ( opinion_account.options.extensions.value.num_son.valid() )
             {
-               for(const auto& num_sidechain_son : *opinion_account.options.extensions.value.num_son) {
+               auto active_sidechains = active_sidechain_types(d.head_block_time());
+               auto num_son_map = *opinion_account.options.extensions.value.num_son;
+
+               if ( num_son_map.size() != active_sidechains.size())
+               {
+                  for (const auto& num_sidechain_son : num_son_map)
+                  {
+                     FC_ASSERT(active_sidechains.find(num_sidechain_son.first) != active_sidechains.end());
+                     active_sidechains.erase(num_sidechain_son.first);
+                  }
+
+                  for (auto missing_num_son : active_sidechains)
+                  {
+                     num_son_map[missing_num_son] = 0;
+                  }
+               }
+
+               for(const auto& num_sidechain_son : num_son_map) {
                   const auto sidechain = num_sidechain_son.first;
                   const auto& num_son = num_sidechain_son.second;
                   if (num_son <= props.parameters.maximum_son_count()) {

libraries/chain/include/graphene/chain/protocol/account.hpp

@@ -36,21 +36,16 @@ namespace graphene { namespace chain {
    bool is_cheap_name( const string& n );
 
    /// These are the fields which can be updated by the active authority.
-   struct account_options
+   struct   account_options
    {
       struct ext
       {
          /// The number of active son members this account votes the blockchain should appoint
          /// Must not exceed the actual number of son members voted for in @ref votes
-         optional< flat_map<sidechain_type, uint16_t> > num_son = []{
-            flat_map<sidechain_type, uint16_t> num_son;
-            for(const auto& active_sidechain_type : all_sidechain_types){
-               num_son[active_sidechain_type] = 0;
-            }
-            return num_son;
-         }();
+         optional< flat_map<sidechain_type, uint16_t> > num_son;
       };
 
+
       /// The memo key is the key this account will typically use to encrypt/sign transaction memos and other non-
       /// validated account activities. This field is here to prevent confusion if the active authority has zero or
       /// multiple keys in it.

libraries/wallet/wallet.cpp

@@ -2838,8 +2838,24 @@ public:
          if (!votes_removed)
             FC_THROW("Account ${account} is already not voting for SON ${son}", ("account", voting_account)("son", son));
       }
+      auto active_sidechains = active_sidechain_types(time_point::now());
+      auto num_son_map = *voting_account_object.options.extensions.value.num_son;
+
+      if ( num_son_map.size() != active_sidechains.size())
+      {
+         for (const auto& num_sidechain_son : num_son_map)
+         {
+            FC_ASSERT(active_sidechains.find(num_sidechain_son.first) != active_sidechains.end());
+            active_sidechains.erase(num_sidechain_son.first);
+         }
+
+         for (auto missing_num_son : active_sidechains)
+         {
+            num_son_map[missing_num_son] = 0;
+         }
+      }
       FC_ASSERT( voting_account_object.options.extensions.value.num_son.valid() , "Invalid son number" );
-      (*voting_account_object.options.extensions.value.num_son)[sidechain] = desired_number_of_sons;
+      num_son_map[sidechain] = desired_number_of_sons;
 
       account_update_operation account_update_op;
       account_update_op.account = voting_account_object.id;