use pipefail to force exit when `npm install` fails.

bin/compile

 #!/usr/bin/env bash
 
-# fail fast
-set -e
-
-# enable debugging
-# set -x
+set -e            # fail fast
+set -o pipefail   # don't ignore piped exit codes
+# set -x          # enable debugging
 
 # Configure directories
 build_dir=$1

bin/test

@@ -66,6 +66,11 @@ testProfileCreated() {
   assertCapturedSuccess
 }
 
+testInvalidDependency() {
+  compile "invalid-dependency"
+  assertCapturedError 1 "not in the npm registry"
+}
+
 testNodeModulesCached() {
   cache=$(mktmpdir)
   compile "caching" $cache