TBTR: Fix attempting to get sprite for new virtual engine before marking as virtual

src/train_cmd.cpp

@@ -4209,8 +4209,6 @@ Train* CmdBuildVirtualRailVehicle(EngineID eid, bool lax_engine_check, StringID
 	v->SetFrontEngine();
 	v->SetEngine();
 
-	v->UpdateViewport(true, false);
-
 	if (rvi->railveh_type == RAILVEH_MULTIHEAD) {
 		AddRearEngineToMultiheadedTrain(v);
 	} else {
@@ -4222,6 +4220,8 @@ Train* CmdBuildVirtualRailVehicle(EngineID eid, bool lax_engine_check, StringID
 		train_part->SetVirtual();
 	}
 
+	v->UpdateViewport(true, false);
+
 	v->ConsistChanged(CCF_ARRANGE);
 
 	CheckConsistencyOfArticulatedVehicle(v);