Apply suggestion. Better lsn file check

files/gitlab-ctl-commands-ee/lib/geo/promote_to_primary_node.rb

@@ -99,7 +99,9 @@ module Geo
       return nil unless File.exist?(geo_pitr_file)
-      File.read(geo_pitr_file)
+      lsn = File.read(geo_pitr_file)
+
+      lsn.empty? ? nil : lsn
     end
     def built_recovery_setting_for_pitr(lsn)