exit() method from Listenable trait is not implemented for labeled contexts. As a result, fn exit_or(&mut self, _ctx: &OrContext<'a>) not being called when walking the generated tree :(

boolExpr:
  ...
  | boolExpr '||'  boolExpr                                  #or
  ...

See also impl<'input, 'a> Listenable<dyn LabelsListener<'input> + 'a> for AddContext<'input>