FIX: Resetting selectable avatars was failing (#16302)

lib/site_setting_extension.rb

@@ -508,6 +508,8 @@ module SiteSettingExtension
           value = current[name]
         end
 
+        return [] if value.empty?
+
         value = value.split("|").map(&:to_i)
         uploads_list = Upload.where(id: value).to_a
         uploads[name] = uploads_list if uploads_list

spec/lib/site_setting_extension_spec.rb

@@ -254,8 +254,11 @@ describe SiteSettingExtension do
   end
 
   describe "remove_override" do
+    fab!(:upload) { Fabricate(:upload) }
+
     before do
       settings.setting(:test_override, "test")
+      settings.setting(:image_list_test, "", type: :uploaded_image_list)
       settings.refresh!
     end
     it "correctly nukes overrides" do
@@ -263,6 +266,12 @@ describe SiteSettingExtension do
       settings.remove_override!(:test_override)
       expect(settings.test_override).to eq("test")
     end
+
+    it "correctly nukes overrides for image list type setting" do
+      settings.image_list_test = "#{upload.id}"
+      settings.remove_override!(:image_list_test)
+      expect(settings.image_list_test).to be_empty
+    end
   end
 
   describe "string setting" do