Fix crash in station joining highlight

src/citymania/cm_station_gui.cpp

@@ -155,12 +155,29 @@ void OnStationTileSetChange(const Station *station, bool adding, StationType typ
     if (station == _viewport_highlight_station) MarkCoverageAreaDirty(_viewport_highlight_station);
 }
 
+void OnStationDeleted(const Station *station) {
+    if (_highlight_station_to_join == station) {
+        MarkCoverageAreaDirty(station);
+        _highlight_station_to_join = nullptr;
+    }
+}
+
 const Station *_last_built_station;
 void OnStationPartBuilt(const Station *station) {
     _last_built_station = station;
     CheckRedrawStationCoverage();
 }
 
+void OnStationRemoved(const Station *station) {
+    if (_last_built_station == station) _last_built_station = nullptr;
+    if (_station_to_join == station) {
+        // TODO MarkJoinHighlight
+        MarkCoverageAreaDirty(station);
+        _station_to_join = nullptr;
+    }
+}
+
+
 const Station *CheckClickOnDeadStationSign() {
     int x = _cursor.pos.x;
     int y = _cursor.pos.y;

src/citymania/cm_station_gui.hpp

@@ -27,6 +27,7 @@ enum class StationBuildingStatus {
 bool UseImprovedStationJoin();
 void OnStationTileSetChange(const Station *station, bool adding, StationType type);
 void OnStationPartBuilt(const Station *station);
+void OnStationRemoved(const Station *station);
 void PlaceRoadStop(TileIndex start_tile, TileIndex end_tile, RoadStopType stop_type, bool adjacent, RoadType rt, StringID err_msg);
 void HandleStationPlacement(TileIndex start, TileIndex end);
 void PlaceRail_Station(TileIndex tile);

src/station.cpp

@@ -30,6 +30,8 @@
 
 #include "table/strings.h"
 
+#include "citymania/cm_station_gui.hpp"
+
 #include "safeguards.h"
 
 /** The pool of stations. */
@@ -87,6 +89,8 @@ Station::Station(TileIndex tile) :
  */
 Station::~Station()
 {
+	citymania::OnStationRemoved(this);
+
 	for (Town *t : Town::Iterate()) {
 		// Using poiter comparison instead of cycling cargos
 		if (t->ad_ref_goods_entry >= this->goods &&