return only if no stdout

debomatic-webui/lib/stats.coffee

@@ -37,6 +37,7 @@ get_disk_usage = (cb) ->
             if stderr?
                 error = '\n\t' + stderr.replace(/\n/g, '\n\t')
             utils.errors_handler "disk usage error:", error
+            if not stdout?
                 return
         result = {}
         others = 0