Fix run arg order and abort on any failure.

action.yml

@@ -22,5 +22,5 @@ runs:
         key: cache-apt-pkgs_${{ inputs.cache_key }}
 
     - name: Install Packages
-      run: ${{ github.action_path }}/run.sh / ~/cache-apt-pkgs ${{ inputs.packages }}
+      run: ${{ github.action_path }}/run.sh ~/cache-apt-pkgs / ${{ inputs.packages }}
       shell: bash

run.sh

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+# Exit on any failure.
+set -e
+
 # Directory that holds the cached packages.
 cache_dir=$1
 # Root directory to untar the cached packages to.