Fix crash on opening notification panel
Fix crash on opening notification panel

The check for pending edits needed a null guard, since the notification
panel uses MessagePanel but is not associated with a specific room.

Signed-off-by: Robin Townsend <474ee9ee179b0ecf0bc27408079a0b15eda4c99d@robin.town>

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk