Strew analyzer with files without test crashes worker

Description

The worker crashed when no test files were present in a submission and the strew analyzer was run.

Changes

Added a missing return statement that fixes the problem.

Additions

A return statement.

Closes #224 (closed)

Test and Review

To be filled in by the reviewers

• All of the methods are commented to expectation

• The methods are tested to satisfaction

• There are no unnecessary files present in the MR

• The continuous integration has no problems with the MR

• The MR is filled in as requested (including labels, milestones, and reviewers)

• The documentation is up-to-date

• All nullable parameters are marked as such