[Crash] ColumnView crashes when going back while loading large folder

[jeremypw]

What Happened?

Opened a folder in ColumnView and the clicked on a subfolder containing a very large number of files. Before all the files were loaded, clicked on another subfolder contained many files. After a pause Files crashed with the message
ERROR:../src/View/AbstractDirectoryView.vala:2744:files_abstract_directory_view_schedule_thumbnail_color_tag_timeout: assertion failed: (slot is Files.AbstractSlot && slot.directory != null) Bail out! ERROR:../src/View/AbstractDirectoryView.vala:2744:files_abstract_directory_view_schedule_thumbnail_color_tag_timeout: assertion failed: (slot is Files.AbstractSlot && slot.directory != null) Aborted

This may not happen every time but is likely to happen with large folders

Steps to Reproduce

1. Open ColumnView
2. Click on a large subfolder
3. Click on another large subfolder

Expected Behavior

The loading folder should be cancelled and the second one begin to load without any crashes

OS Version

7.x (Horus)

Software Version

Latest release (I have run all updates)

Log Output

No response

Hardware Info

No response