[#73] Revert `StepOut` changes

Description

Problem: StepOut shouldn't really do a step back when there is no lambda to step out from. Instead, it should terminate like the old behavior.

Solution: Revert recent StepOut changes, add a test to avoid this problem in the future.

Related issue(s)

Resolves #73 (closed)

✅ Checklist for your Merge Request

Related changes (conditional)

• Dependencies

  • We depend only on package versions that have been released on hackage (i.e., we don't fetch dependencies from git repositories). Failing that, we depend only on commits from the project's master branch, and not from any other branch.

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • Root README and other README.md files
    • Haddock
    • docs/
  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

Stylistic guide (mandatory)

• My commits comply with the following policy.
• My code complies with the style guide.

Implementation concerns

• VSCode plugin
  • If I changed values in the initial configuration for launch.json, I also searched for them in code and updated accordingly. I keep the default configurations and default values for not listed fields in match.