if a file is referenced in template-info.json but doesn't exist and you then create the file, the diagnostic in template-info.json doesn't go away until you edit it.
if a file is referenced in template-info.json and you delete it, you don't get a diagnostic in template-info.json until you edit it.
if you delete a template-info.json, all of the diagnostics for the template files should go away but they don't until you restart.
The current symptoms are: