Error purging old files

[JimBacon]

While debugging a fault (which turned out to be due to some malformed data) I saw the error message

2022-09-08 11:35:21 +01:00 --- error: 
  Uncaught ErrorException: 
    unlink(D:\websites\warehouse\download/\download-6319b73b225071.19838332.json): 
      No such file or directory in file D:/websites/warehouse/application/helpers/warehouse.php on line 156

The cause of the unlink error in this case is the /\ file separator.
The purgeOldFiles() function where the error is happening specifies that it should be called with a 'folder path relative to the DOCROOT, without leading or trailing slash.'
However it had been called with a $path having a trailing '/'
This happens in a few places and needs fixing.

Note, the code at that point is supposed to supress errors caused by problems unlinking files. Indeed, I think it was succeeding, but when I hit a subsequent error, this supressed error was being logged. I.e. the error I was having a problem with had nothing to do with the message I was seeing which was confusing.