Exporting: include a warning if not possible

Hello,
I wanted to export my music to my SDHC card. After a while I got the message that an error occurred. I guess this was because I wanted to export my folder with a lot of playlists (with a capacity of 35GB) to an SD card with a capacity that was not big enough (32GB). However I am not completely sure that was the actual reason of the error message.

Anyway, if the device's capacity is not large enough for what the DJ wants to export, that should be checked by rekordbox before exporting tracks. In this way a lot of time can be saved.

Thanks!