This message was deleted.

Solved this by running yarn install (didn't really install anything) and pushing again. Also added a project.toml with

[[requires]]
    name = "node"
    version = "~10"

but not sure if it's that or the yarn.lock/node_modules presence that made execjs work.

@lively-umbrella-63572 some insight: currently the default epinio staging workflow uses

creator/lifecycle

which has mixed/unclear support for the project.toml - unlike

pack

where it is more obvious. This is an area we're actively working to clear up. (as mentioned in the other thread)

After more trial and error,

project.toml

didn't seem to make a difference in the end. I ended up installing another gem (mini_racer), which makes execjs find another js runtime and node was no longer required (not sure how that actually works internally, it just didn't complain anymore and the build finally worked).