Add the test.mustache template to lib/templates/test.mustache Login as admin Ensure your browser's developer console is open Navigate to Development > Debugging in site administration Set Debug messages to Developer and save changes Navigate to Development > Template library in site administration Search for, and click on, the "core/test" template Confirm you see "Could not parse json example context for template." in the console, followed by a stacktrace Navigate to Development > Debugging in site administration Set Debug messages to None and save changes Navigate to Development > Template library in site administration Search for, and click on, the "core/test" template Confirm you don't see any logged message from the template library in the console