Update the test generator: comments error handling and bool to string

[IsaacG]

No description provided.

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

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[glennj]

Does this PR include the "missing newline at EOF" fix from the awk track?

[IsaacG]

This writes the trailing newline.

[IsaacG]

Does this PR include the "missing newline at EOF" fix from the awk track?

Yup. Line 144.