[flang] Merge pull request flang-compiler/f18#465 from flang-compiler/pmk-fix-tim

Fix crash reported by Tim

Original-commit: flang-compiler/f18@6ad320265a54acafd724dc28f6a1e7a6a875246c
Reviewed-on: https://github.com/flang-compiler/f18/pull/465
tree: ba46e5e007d9681909dad7ad6f71817c1fa95734
  1. flang/