verify: ignore resolve errors for broken NS records

verify.rb

@@ -68,8 +68,9 @@ class ChinaListVerify
             server = [server] unless server.is_a? Array
             resolver = Resolv::DNS.new(nameserver: server)
         end
+        begin
             if !with_glue
-            resolver.getresources(domain, rdtype)
+                return resolver.getresources(domain, rdtype)
             else
                 # Workaround for https://github.com/ruby/resolv/issues/27
                 result = []
@@ -86,6 +87,13 @@ class ChinaListVerify
                 }
                 return result, glue
             end
+        rescue Exception => e
+            if !with_glue
+                return []
+            else
+                return [], []
+            end
+        end
     end
 
     def get_ns_for_tld(tld)