This file contains all ‘NUL’ bytes, is corrupt and unrecoverable. The only way to get it back is through a backup. If you do not have backup, now is the time for you to consider doing that. Some other Windows user report this:
https://forum.shotcut.org/search?q=fail%20open%20NUL
We have found no evidence that Shotcut does this. Shotcut writes to a temporary file, validates it, and then safely replaces the old file only if it was valid. Users of other software report similar problems. It might be linked to how Windows filesystem works when the computer crashes. It might also be due to a corrupt file system or hardware.
See also Failed to Open