Fix error page when DB is down (#729)

Author: vertism

app/views/layouts/application.html.erb

@@ -38,7 +38,7 @@
 <% end %>
 
 <% if dev_tools_enabled? %>
-  <%= render partial: 'layouts/developer_tools' if current_disclosure_report.try(:completed?) %>
+  <%= render partial: 'layouts/developer_tools' if controller_name != "errors" && current_disclosure_report.try(:completed?) %>
 <% end %>
 
 <%= render template: 'layouts/govuk_template', layout: false %>