refactor: minor code modification

src/controllers/application.cr

@@ -160,6 +160,7 @@ abstract class Application < ActionController::Base
   # 404 if resource not present
   @[AC::Route::Exception(Error::NotFound, status_code: HTTP::Status::NOT_FOUND)]
   @[AC::Route::Exception(PgORM::Error::RecordNotFound, status_code: HTTP::Status::NOT_FOUND)]
+  @[AC::Route::Exception(Error::TenantNotFound, status_code: HTTP::Status::NOT_FOUND)]
   def sql_record_not_found(error) : CommonError
     Log.debug { error.message }
     render_error(error)

src/controllers/calendars.cr

@@ -61,7 +61,7 @@ class Calendars < Application
     all_calendars.concat(candidate_calendars)
     calendars = all_calendars.to_a
 
-    render :not_found, json: "no tenants exist" if calendars.empty?
+    raise Error::TenantNotFound.new("no tenants exist") if calendars.empty?
 
     # perform availability request
     period_start = Time.unix(period_start)

src/error.cr

@@ -29,6 +29,9 @@ class Error < Exception
   class NotFound < Error
   end
 
+  class TenantNotFound < Error
+  end
+
   class BadUpstreamResponse < Error
   end