message: Handle Top start environment
  Summary: Avoid calling `bindings()` on Top environments.
diff: @@ -524,7 +524,7 @@ AnalysisResult analyze(ControlFlowGraph& cfg) {
  size_t sources_count;
  {
  auto env = analysis::create_start(ret.rdefs);
  - sources_count = env.bindings().size();
  + sources_count = env.is_top() ? 0 : env.bindings().size();
  ret.iter->run(env);
  }
  