If you do get that again, could you click on the link and report the code lines it points to?
I think that it is reporting that it can't access the Node-RED settings (
RED.settings.uibuilderTemplates which is a property passed back from the .js file via the options to
I can't see anything else that might go wrong in that function as it is mostly jQuery.
I've put in a test for the next release in the
populateTemplateDropdown function so that it outputs a suitable error if the setttings aren't accessible.