Fix flash messages on sign-in [SCI-5386]

app/helpers/application_helper.rb

@@ -40,6 +40,10 @@ module ApplicationHelper
     controller_name == 'my_modules' && !@repository.nil?
   end
 
+  def displayable_flash_type?(type)
+    %w(success warning error notice).include?(type)
+  end
+
   def flash_alert_class(type)
     case type
     when 'success'

app/views/shared/_flash_alerts.html.erb

@@ -1,5 +1,7 @@
 <div id="notifications">
   <% flash.each do |type, message| %>
+    <% next unless displayable_flash_type?(type) %>
+
     <div id="alert-flash" class="alert <%= flash_alert_class(type) %> alert-dismissable alert-floating">
         <span class="fas <%= flash_icon_class(type) %>"></span>
         <span class="message"><%= sanitize_input(message) %></span>