From 00bb10d14af4a7a052ab68ca9cd613c039172830 Mon Sep 17 00:00:00 2001
From: Patrick Gansterer <paroga@paroga.com>
Date: Mon, 7 Sep 2020 13:55:48 +0200
Subject: [PATCH] Fix CreateStockEvents migration for DBs without Delivery
 and/or StockTaking

---
 db/migrate/20181204070000_create_stock_events.rb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/db/migrate/20181204070000_create_stock_events.rb b/db/migrate/20181204070000_create_stock_events.rb
index 50974900..6de2c6cc 100644
--- a/db/migrate/20181204070000_create_stock_events.rb
+++ b/db/migrate/20181204070000_create_stock_events.rb
@@ -11,7 +11,9 @@ class CreateStockEvents < ActiveRecord::Migration[4.2]
       dir.up do
         change_column_default :stock_events, :type, nil
 
-        diff = [StockEvent.maximum(:id) + 1 - StockTaking.minimum(:id), 0].max
+        stock_event_max = StockEvent.maximum(:id) || 0
+        stock_taking_min = StockTaking.minimum(:id) || 0
+        diff = [stock_event_max + 1 - stock_taking_min, 0].max
 
         execute "UPDATE stock_changes SET stock_event_id = stock_taking_id + #{diff}
           WHERE stock_taking_id IS NOT NULL"