Fix bug in tile generation causing exception on None shapefile record

tile_gen/tile_index.py

@@ -70,8 +70,8 @@ def shapes_generator(input_files, prev_shapefile, shared_bbox=False):
             # the old shapefile includes a file that we no longer want
             # keep going through the existing shapes until we find one we
             # do want
-            location, shape_info = next(prev_shapes, default_shape)
             yield 'removed', location, shape_info
+            location, shape_info = next(prev_shapes, default_shape)
             continue
         yield 'existing', location, shape_info
         location, shape_info = next(prev_shapes, default_shape)