Gap fill from HS should halt on network disconnection

[MidhunSureshR]

and should resume when connection is regained This PR:

• Wait for network reconnection before retrying gap fill
• UI Improvements:
  • Errors can optionally show a spinner (eg when waiting for reconnection)
  • Other errors show no spinner
  • Show either "Not Loading" or the error itself but not both
  • Not Loading should not show a spinner