Consistent error message (incl. stacktrace) when evaluation failed

Summary of changes

We had a problem when deploying a service because it failed running a command. The only error we got was:

▸ Evaluation failed with: argument error

We did not know what is causing the error and where it is coming from, so we were forced to monkey-patch distillery to get more details. We've updated the rescue-block in Mix.Releases.Runtime.Control.eval/2 to give us the error messages and the stacktrace. After doing so, we got this.

▸  Evaluation failed: argument error
▸      (stdlib) :ets.insert(:otter_snapshot_store, {...}]})
▸      (otter_lib) /src/deps/otter_lib/src/otter_lib_snapshot_count.erl:59: :otter_lib_snapshot_count.snapshot/2
▸      (otter) /src/deps/otter/src/otter_filter.erl:60: :otter_filter.do_actions/5
▸      (tracing) lib/tracing/adapter/otter.ex:49: Tracing.Adapter.Otter.finish_span/1
▸      (tracing) lib/tracing.ex:93: Tracing.finish_span/2
▸      (tracing) lib/tracing/ecto/repo.ex:168: Tracing.Ecto.Repo.trace/3
▸      (stdlib) timer.erl:197: :timer.tc/3
▸      (ecto) lib/ecto/migration/runner.ex:25: Ecto.Migration.Runner.run/6

Yay! :tada: We forgot to start otter.

This PR updates Mix.Releases.Runtime.Control.eval/2 to have a consistent error message (incl. stacktrace).

Checklist

[ ] New functions have typespecs, changed functions were updated
[ ] Same for documentation, including moduledocs
[ ] Tests were added or updated to cover changes
[x] Commits were squashed into a single coherent commit

Licensing/Copyright

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I certify that I own, and have sufficient rights to contribute, all source code and related material intended to be compiled or integrated with the source code for Distillery (the "Contribution"). My Contribution is licensed under the MIT License.

bitwalker / distillery