luci-app-nlbwmon: fix nil value concat
authorJo-Philipp Wich <jo@mein.io>
Tue, 2 Oct 2018 17:20:53 +0000 (19:20 +0200)
committerJo-Philipp Wich <jo@mein.io>
Tue, 2 Oct 2018 17:20:53 +0000 (19:20 +0200)
commitfb859e602b1254c5d199d7f641f6b6717edd01cf
treed0c1a1b6ac59e80c00fb90e18f40e1d7e3a91bde
parenta90001419e207a9dbe3f78af4363b6e6a1d77530
luci-app-nlbwmon: fix nil value concat

Do not concatenate the yet undefined mtime variable to avoid a controller
error with backtrace.

Fixes: b3642f476 ("luci-app-nlbwmon: add proper file names for json and csv exports.")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
applications/luci-app-nlbwmon/luasrc/controller/nlbw.lua