Merge pull request #1097 from SecretsOTheP/null_ptr_fixes

Null ptr fixes

zone/zone.cpp

@@ -857,12 +857,14 @@ void Zone::Shutdown(bool quiet)
 	while (!zone->npctable.empty()) {
 		itr = zone->npctable.begin();
 		delete itr->second;
+		itr->second = nullptr;
 		zone->npctable.erase(itr);
 	}
 
 	while (!zone->merctable.empty()) {
 		itr = zone->merctable.begin();
 		delete itr->second;
+		itr->second = nullptr;
 		zone->merctable.erase(itr);
 	}
 
@@ -872,6 +874,7 @@ void Zone::Shutdown(bool quiet)
 	while (!zone->ldon_trap_list.empty()) {
 		itr4 = zone->ldon_trap_list.begin();
 		delete itr4->second;
+		itr4->second = nullptr;
 		zone->ldon_trap_list.erase(itr4);
 	}
 	zone->ldon_trap_entry_list.clear();
@@ -1707,6 +1710,7 @@ bool Zone::Depop(bool StartSpawnTimer) {
 	while(!npctable.empty()) {
 		itr = npctable.begin();
 		delete itr->second;
+		itr->second = nullptr;
 		npctable.erase(itr);
 	}
 
@@ -1723,6 +1727,7 @@ void Zone::ClearNPCTypeCache(int id) {
 		auto iter = npctable.begin();
 		while (iter != npctable.end()) {
 			delete iter->second;
+			iter->second = nullptr;
 			++iter;
 		}
 		npctable.clear();
@@ -1732,6 +1737,7 @@ void Zone::ClearNPCTypeCache(int id) {
 		while (iter != npctable.end()) {
 			if (iter->first == (uint32)id) {
 				delete iter->second;
+				iter->second = nullptr;
 				npctable.erase(iter);
 				return;
 			}