Ah, brain poisoned by R's return() syntax; check if data is empty, then check data.colnames to make sure column names are passed in

Author: yihui

inst/www/shared/shiny.js

@@ -1195,7 +1195,7 @@
     },
     renderValue: function(el, data) {
       var $el = $(el).empty();
-      if (!data.colnames) return();
+      if (!data || !data.colnames) return;
       var colnames = $.makeArray(data.colnames);
       var header = colnames.map(function(x) {
         return '<th>' + x + '</th>';