Thanks!
Was just looking over the docs and saw this:
Optionally, you can provide a timeout (in milliseconds) for specifying how long to wait before aborting. Note: The default timeout is 5 seconds.
Builds will never be as fast on CI as they are locally, I wonder if this step is taking longer than the default timeout and silently dying.
I think the main issue though is that chrome is not installed in that image. Can you use the 9.4-browsers image instead?