Fix that in-use Workflows couldn't be deleted

app/models/workflow.rb

@@ -4,7 +4,8 @@ class Workflow < ApplicationRecord
     { name: "In progress", color: "var(--color-card-3)" }
   ]
 
-  has_many :stages, dependent: :delete_all
+  has_many :stages, dependent: :destroy
+  has_many :collections, dependent: :nullify
 
   after_create_commit :create_default_stages
 

app/models/workflow/stage.rb

@@ -1,6 +1,8 @@
 class Workflow::Stage < ApplicationRecord
   belongs_to :workflow, touch: true
 
+  has_many :cards, dependent: :nullify
+
   before_validation :assign_random_color, on: :create
 
   private