Add missing errors module.
Add missing errors module.

njwilson23/rasterio,perrygeo/rasterio,perrygeo/rasterio,clembou/rasterio,brendan-ward/rasterio,perrygeo/rasterio,youngpm/rasterio,youngpm/rasterio,kapadia/rasterio,brendan-ward/rasterio,kapadia/rasterio,njwilson23/rasterio,brendan-ward/rasterio,clembou/rasterio,njwilson23/rasterio,clembou/rasterio,youngpm/rasterio,kapadia/rasterio