places view: Avoid a crash in finalize
places view: Avoid a crash in finalize

When the places view is finalized before the network loading
is finished, the async operation is cancelled, and the callback
accesses the places view while it is already in a state of
disrepair. Avoid that access.

jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,jadahl/gtk,chergert/gtk,chergert/gtk,chergert/gtk,alexlarsson/gtk,jadahl/gtk,chergert/gtk,jigpu/gtk,chergert/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,davidgumberg/gtk,alexlarsson/gtk,chergert/gtk,davidgumberg/gtk,alexlarsson/gtk,davidgumberg/gtk,jigpu/gtk,alexlarsson/gtk,jadahl/gtk,davidgumberg/gtk,alexlarsson/gtk,grubersjoe/adwaita,alexlarsson/gtk,chergert/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,davidgumberg/gtk,davidgumberg/gtk,jigpu/gtk,jadahl/gtk,jigpu/gtk,jigpu/gtk,grubersjoe/adwaita,jigpu/gtk,davidgumberg/gtk,jadahl/gtk,jigpu/gtk