prune-dns: fix syntactical problem in error path

prune-dns: fix syntactical problem in error path

Latent bug. We do not normally hit this branch.

ArgumentError: wrong number of arguments (given 4, expected 0..1)
  /usr/local/lib/ruby/2.6.0/logger.rb:542:in `error'
  /usr/local/bin/prune-dns:39:in `<top (required)>'
diff --git a/bin/prune-dns b/bin/prune-dns
index 4b747e6..2f8a554 100755
--- a/bin/prune-dns
+++ b/bin/prune-dns
@@ -36,10 +36,11 @@ logger = Logger.new($stderr)
 logger.level = verbosity
 
 if instances.any? { |id| id !~ /^[0-9a-f]{17}$/ }
-  logger.error "Those EC2 server ids don't all look right.",
-    "Should be 17 characters 0-9 a-f.",
-    "I got these:", ''
-  logger.error instances
+  logger.error <<~END.gsub(/\n/, ' ')
+    Invalid EC2 instance ID.
+    Expected each ID to be a 17-digit hexadecimal number sans leading i-.
+    Received: #{instances.inspect}
+  END
   exit 1
 end
 

GitHub sha: e6076a6c48ef182bab6913319bcbbb30555733c2