Prevent from segfault OnTriggerEndOverlap

In case the OtherActor is not a Vehicle just return

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Latest
 
+  * Fixed bug in FrictionTrigger causing sometimes server segfault
   * Added attachment type "SpringArmGhost" for cinematic cameras but without doing the collision test.
   * Improved algorithm to move signals out of the road by computing the desired displacement direction.
   * Added `TrafficManager.vehicle_lane_offset(actor, offset)` and `TrafficManager.global_lane_offset(offset)` methods.

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Trigger/FrictionTrigger.cpp

@@ -71,6 +71,9 @@ void AFrictionTrigger::OnTriggerEndOverlap(
   UpdateWheelsFriction(OtherActor, OldFrictionValues);
 
   ACarlaWheeledVehicle *Vehicle = Cast<ACarlaWheeledVehicle>(OtherActor);
+  if(Vehicle == nullptr)
+    return;
+
   TArray<float> CurrFriction = Vehicle->GetWheelsFrictionScale();
 }