Reset PlayerSingleton after ending game instance

Author: Hop311

extension/doc_classes/PlayerSingleton.xml

@@ -39,6 +39,11 @@
 			<description>
 			</description>
 		</method>
+		<method name="reset_player_singleton">
+			<return type="void" />
+			<description>
+			</description>
+		</method>
 		<method name="set_auto_assign_leaders" qualifiers="const">
 			<return type="void" />
 			<param index="0" name="value" type="bool" />

extension/src/openvic-extension/singletons/PlayerSingleton.cpp

@@ -19,6 +19,8 @@ StringName const& PlayerSingleton::_signal_province_selected() {
 }
 
 void PlayerSingleton::_bind_methods() {
+	OV_BIND_METHOD(PlayerSingleton::reset_player_singleton);
+
 	// Player country
 	OV_BIND_METHOD(PlayerSingleton::set_player_country_by_province_number, { "province_number" });
 	OV_BIND_METHOD(PlayerSingleton::get_player_country_capital_position);
@@ -74,6 +76,14 @@ PlayerSingleton::~PlayerSingleton() {
 	singleton = nullptr;
 }
 
+void PlayerSingleton::reset_player_singleton() {
+	// This function is called when a game session ends, so we don't use functions like set_player_country or
+	// unset_selected_province here as they can dereference leftover pointers from the previous game session which
+	// are either already or soon to be invalid.
+	player_country = nullptr;
+	selected_province = nullptr;
+}
+
 // Player country
 void PlayerSingleton::set_player_country(CountryInstance* new_player_country) {
 	if (OV_unlikely(player_country == new_player_country)) {

extension/src/openvic-extension/singletons/PlayerSingleton.hpp

@@ -30,6 +30,8 @@ namespace OpenVic {
 		PlayerSingleton();
 		~PlayerSingleton();
 
+		void reset_player_singleton();
+
 		// Player country
 		[[nodiscard]] constexpr CountryInstance* get_player_country() {
 			return player_country;