Build is not aborted if an error occurs

[edmorley]

If an error occurs during the compile of this buildpack, the build continues on regardless rather than failing, since the bash error on exit mode is not enabled.

For improved reliability, it would be great to add a set -e, or even better, set -euo pipefail.

See also:
http://redsymbol.net/articles/unofficial-bash-strict-mode/

Many thanks :-)