Handle NoMethodError for nil starting_node on Flow

[Taucher2003]

Closes #909

[github-actions]

GitLab Pipeline Action

General information

Link to pipeline: https://gitlab.com/code0-tech/development/sagittarius/-/pipelines/2458763138

Status: Passed
Duration: 3 minutes

Job summaries

rspec: [ee]

Coverage report available at https://code0-tech.gitlab.io/-/development/sagittarius/-/jobs/13960287848/artifacts/tmp/coverage/index.html
Test summary available at https://gitlab.com/code0-tech/development/sagittarius/-/pipelines/2458763138/test_report
Finished in 24.82 seconds (files took 11.51 seconds to load)
1345 examples, 0 failures
Line Coverage: 92.84% (4384 / 4722)
[TEST PROF INFO] Time spent in factories: 00:13.179 (42.59% of total time)

rspec: [ce]

Coverage report available at https://code0-tech.gitlab.io/-/development/sagittarius/-/jobs/13960287846/artifacts/tmp/coverage/index.html
Test summary available at https://gitlab.com/code0-tech/development/sagittarius/-/pipelines/2458763138/test_report
Finished in 22.87 seconds (files took 12.9 seconds to load)
1298 examples, 0 failures
Line Coverage: 92.31% (4216 / 4567)
[TEST PROF INFO] Time spent in factories: 00:12.111 (40.04% of total time)

docs:preview

Documentation preview available at https://code0-tech.gitlab.io/-/development/telescopium/-/jobs/13960334914/artifacts/out/index.html

rubocop

743 files inspected, no offenses detected