ci: Check if components folder exists before trying to tar it.

Currently, the build fails when the build stage doesn't build the components library.
In case there is no dist folder with components that can be packed.
So we have to pack it only when the folder exists.

Fixes #420

.circleci/config.yml

@@ -202,7 +202,14 @@ jobs:
     steps:
       - attach_workspace:
           at: ~/barista
-      - run: cd dist && tar czf components.tar.gz ./components/
+      - run:
+          name: Create components package if it exists
+          command: |
+            if [[ -d ./dist/components ]];
+            then
+              cd dist
+              tar czf components.tar.gz ./components/
+            fi
       - store_artifacts:
           path: dist/components.tar.gz
           destination: barista-components