Attach renderer construction error to the renderer cache
Attach renderer construction error to the renderer cache

This bug resulted in a confusing error returned the _second_ time a
bogus request was sent (first time was good). Fix lacks a testcase.

manueltimita/Windshaft,manueltimita/Windshaft,wsw0108/Windshaft,CartoDB/Windshaft,HydroLogic/Windshaft,manueltimita/Windshaft,CartoDB/Windshaft,HydroLogic/Windshaft,CartoDB/Windshaft,wsw0108/Windshaft,wsw0108/Windshaft,HydroLogic/Windshaft