:art: json => not print "array" when not needed

diff --git a/plug b/plug
index 789a32a73443a580e30f58f87b3beb9bb5d79d6e..257cb4d6e43161abbf899384d6e6a0dcd10c7b5b 160000 (submodule)
--- a/plug
+++ b/plug
@@ -1 +1 @@
-Subproject commit 789a32a73443a580e30f58f87b3beb9bb5d79d6e
+Subproject commit 257cb4d6e43161abbf899384d6e6a0dcd10c7b5b