Allow null slack uid for users creating accounts via email

db/migrate/20250312172534_allow_null_slack_uid.rb

@@ -0,0 +1,5 @@
+class AllowNullSlackUid < ActiveRecord::Migration[8.0]
+  def change
+    change_column_null :users, :slack_uid, true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_03_12_160326) do
+ActiveRecord::Schema[8.0].define(version: 2025_03_12_172534) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
 
@@ -230,7 +230,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_03_12_160326) do
   end
 
   create_table "users", force: :cascade do |t|
-    t.string "slack_uid", null: false
+    t.string "slack_uid"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.string "username"