FYI, this is one of the cases where $^E is more informative than $! (on Windows). For this failure, it would report:

The process cannot access the file because it is being used by another
+ process
[download]

When writing Perl code that will only be run on Windows, I sometimes report $^E as well as or instead of reporting $!. Most of the time it doesn't matter. But there are a few cases where $^E more accurately points to the real source of the failure.