Build on Jenkins does not handle build errors properly

[michaelkleinhenz]

Currently, a build may be deployed to demo.almighty althought it failed building, resulting in just index.html deployed to the server.

I suspect that errors appearing inside the build container are somehow not propagated to the outside Jenkins build. They may just be consumed somewhere.

That one is severe, as it may affect other builds in other projects as we basically just re-used that setup.