fix: show due today if never completed

lib/putzplan/tasks/task.ex

@@ -41,21 +41,25 @@ defmodule Putzplan.Tasks.Task do
                 fragment(
                   "SELECT c.completion FROM \"completed_tasks\" AS c WHERE c.task_id = ? ORDER BY c.completion DESC LIMIT 1",
                   id
-                ) || today()
+                )
               )
 
     calculate :due,
               :date,
               expr(
-                fragment(
-                  # HACK: to cast to date
-                  "SELECT strftime('%F', ?)",
-                  date_add(
-                    last_completed,
-                    repetition_days,
-                    :day
+                if last_completed do
+                  fragment(
+                    # HACK: to cast to date
+                    "SELECT strftime('%F', ?)",
+                    date_add(
+                      last_completed,
+                      repetition_days,
+                      :day
+                    )
                   )
-                )
+                else
+                  today()
+                end
               )
   end
 end