When the rr_loopbacks variable resolved empty, the IN
(${rr_loopbacks:singlequote}) clause expanded to IN (), a SQL
syntax error that blanked the topology panel. Switch to
= ANY(string_to_array('${rr_loopbacks:csv}', ',')), which yields
a no-match (not a syntax error) on an empty variable.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>