Update error message text

api/handler.go

@@ -27,7 +27,7 @@ func NewHandler(fnc interface{}) (handler, error) {
 	//arg[0] must be a struct for params. It may be an empty struct, but
 	//all public fields require a json tag which we will use to math the URL param name
 	if err := validateStructType(fncType.In(0)); err != nil {
-		return h, errors.Wrapf(err, "second arg %v is not valid params struct type", fncType.In(0))
+		return h, errors.Wrapf(err, "first arg %v is not valid params struct type", fncType.In(0))
 	}
 	h.RequestParamsType = fncType.In(0)