Bug Fix: Crasher if a server group is deleted with active servers that match only said group.

Author: jhuckaby

lib/monitor.js

@@ -1034,6 +1034,8 @@ class Monitoring {
 		// scan all candidates considering sort_order
 		grps.forEach( function(id) {
 			var group_def = Tools.findObject( self.groups, { id });
+			if (!group_def) return;
+			
 			if (group_def.sort_order < lowest_sort_order) {
 				lowest_sort_order = group_def.sort_order;
 				best_match = group_def;