Fix #18413: Trying to set tooltip using null vehicle (#21662)

distribution/changelog.txt

@@ -6,6 +6,7 @@
 - Improved: [#21599] Currency signs now use non-breaking spaces.
 - Change: [#21529] Classify “Southern Sands”, “Tiny Towers”, “Nevermore Park”, “Pacifica” as expert scenarios.
 - Fix: [#910] Extra viewport does not preserve the location when rotating.
+- Fix: [#18413] Crash when mouse over a hacked train.
 - Fix: [#20338] Cannot select Scenery Picker or Scatter Tool when the scenery recolouring tool is active.
 - Fix: [#21419] Cannot place walls underground beneath sloped tiles with clearance checks disabled.
 - Fix: [#21434] Number of guests overflows in objective text.

src/openrct2/ride/Vehicle.cpp

@@ -5055,6 +5055,8 @@ void Vehicle::SetMapToolbar() const
     if (curRide != nullptr && curRide->type < RIDE_TYPE_COUNT)
     {
         const Vehicle* vehicle = GetHead();
+        if (vehicle == nullptr)
+            return;
 
         size_t vehicleIndex;
         for (vehicleIndex = 0; vehicleIndex < std::size(curRide->vehicles); vehicleIndex++)