chore: enable pipefail for snapcraft.yaml.sh

Trap empty `NODE_VERSION`, e.g. if fetching `index.tab` fails.

Refs: #38

Author: richardlau

snapcraft.yaml.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-set -xe
+set -euxo pipefail
 
 __dirname="$(CDPATH= cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 STRIP_NPX=no