FIX: blanking theme field was not properly removing it

app/models/theme.rb

@@ -213,7 +213,7 @@ class Theme < ActiveRecord::Base
     field = theme_fields.find{|f| f.name==name && f.target == target_id}
     if field
       if value.blank?
-        field.destroy
+        theme_fields.delete field.destroy
       else
         if field.value != value
           field.value = value

spec/controllers/admin/themes_controller_spec.rb

@@ -69,7 +69,7 @@ describe Admin::ThemesController do
       end
 
       it 'updates a theme' do
-
+        #focus
         theme = Theme.new(name: 'my name', user_id: -1)
         theme.set_field(:common, :scss, '.body{color: black;}')
         theme.save
@@ -80,7 +80,10 @@ describe Admin::ThemesController do
             theme: {
           child_theme_ids: [child_theme.id],
           name: 'my test name',
-          theme_fields: [name: 'scss', target: 'common', value: 'body{color: red;}']
+          theme_fields: [
+            { name: 'scss', target: 'common', value: '' },
+            { name: 'scss', target: 'desktop', value: 'body{color: blue;}' }
+          ]
         }
         expect(response).to be_success
 
@@ -88,8 +91,8 @@ describe Admin::ThemesController do
 
         fields = json["theme"]["theme_fields"]
 
+        expect(fields.first["value"]).to eq('body{color: blue;}')
         expect(fields.length).to eq(1)
-        expect(fields.first["value"]).to eq('body{color: red;}')
 
         expect(json["theme"]["child_themes"].length).to eq(1)