check email is not empty

app/controllers/discourse_donations/charges_controller.rb

@@ -7,7 +7,7 @@ module DiscourseDonations
     skip_before_filter :verify_authenticity_token, only: [:create]
 
     def create
-      if email.nil?
+      if email.nil? || email.empty?
         response = {'message' => 'Please enter your email address'}
       elsif create_account && params[:username].nil?
         response = {'message' => 'Please enter a username'}

spec/controllers/discourse_donations/charges_controller_spec.rb

@@ -17,7 +17,13 @@ module DiscourseDonations
     end
 
     it 'responds ok when the email is empty' do
-      post :create, { }
+      post :create, { create_account: 'true', email: '' }
+      expect(body['message']).to eq('Please enter your email address')
+      expect(response).to have_http_status(200)
+    end
+
+    it 'responds ok when the email is empty' do
+      post :create, { create_account: 'false' }
       expect(body['message']).to eq('Please enter your email address')
       expect(response).to have_http_status(200)
     end