Add null checks

Author: ansoncfit

src/main/java/com/conveyal/r5/labeling/NoSteepInclinesTraversalPermissionLabeler.java

@@ -13,8 +13,10 @@ public class NoSteepInclinesTraversalPermissionLabeler extends USTraversalPermis
     Double maxIncline;
     boolean stepFree;
     public NoSteepInclinesTraversalPermissionLabeler (TransportNetworkConfig config) {
-        if (config.maxIncline != null) this.maxIncline = config.maxIncline;
-        this.stepFree = config.stepFree;
+        if (config != null) {
+            if (config.maxIncline != null) this.maxIncline = config.maxIncline;
+            this.stepFree = config.stepFree;
+        }
     }
     @Override
     public RoadPermission getPermissions(Way way) {

src/main/java/com/conveyal/r5/streets/StreetLayer.java

@@ -227,12 +227,12 @@ public StreetLayer(TransportNetworkConfig config) {
                         "Unknown traversal permission labeler: " + config.traversalPermissionLabeler
                 );
             };
+
+            stepFree = config.stepFree;
+            
         } else {
             permissionLabeler = new USTraversalPermissionLabeler();
         }
-
-        stepFree = config.stepFree;
-
     }
 
     /** Load street layer from an OSM-lib OSM DB */