v0.4.8 crashes indexing Canvas LMS on empty parent relationship symbol #260

Input

• Repository: https://github.com/instructure/canvas-lms
• Commit: 1c9f0bb8013ed69c4f2efe11fd483025469b7e6c
• Platform: GitHub Actions ubuntu-latest, x86_64
• scip-ruby: scip-ruby-v0.4.8
• The repository has no sorbet/config.

Reproduction

From the repository root:

curl -fsSLO https://github.com/sourcegraph/scip-ruby/releases/download/scip-ruby-v0.4.8/scip-ruby-asserts-x86_64-linux
chmod +x scip-ruby-asserts-x86_64-linux
./scip-ruby-asserts-x86_64-linux --index-file index.scip .

The ordinary scip-ruby-x86_64-linux release binary exits on signal 11. The assertions build makes the failure actionable and exits on signal 4:

Exception::raise(): scip_indexer/SCIPSymbolRef.cc:145 enforced condition !rel.symbol().empty() has failed

Backtrace:
  UntypedGenericSymbolRef::saveParentRelationships()
  SCIPState::saveParentRelationships()
  SCIPState::saveDefinition()
  CFGTraversal::emitLocalOccurrence()
  CFGTraversal::traverse()
  SCIPSemanticExtension::typecheck()

spec/models/assignment_spec.rb:13269: Failed to process tree

The same invariant failure is emitted for many files before the process exits, including spec/apis/v1/assignments_api_spec.rb, spec/models/submission_spec.rb, and spec/models/course_spec.rb.

Expected

Indexing completes, or unsupported source constructs are skipped with diagnostics instead of terminating the indexer.