Log failed commands

[Lex-2008]

run scripts in set -e mode, and print if a command fails

Something like:

https://unix.stackexchange.com/questions/21930/last-failed-command-in-bash
https://stackoverflow.com/questions/3822621/how-to-exit-if-a-command-failed

Note, however, that this is busybox ash, not bash :)