update error return values to better match api
update error return values to better match api

raintank/raintank-metric,raintank/metrictank,replay/metrictank,raintank/metrictank,raintank/raintank-metric,raintank/metrictank,raintank/metrictank,raintank/raintank-metric,replay/metrictank,replay/metrictank,replay/metrictank