Refs Block Cloning Processing fails on a single file

[TnTBass]

Describe the bug
When processing the blockstats for a single file, an error occurs as more than one file is needed to gather information.

To Reproduce
Steps to reproduce the behavior:

1. Have a single .vbk file in a directory (an accompanying .vbm is OK, as .vbm's are ignored)
2. Run the veeam_refs_savings.ps1 manually against the drive containing a directory with that single .vbk file.
3. Watch an error being produced
   Exception calling "Parse" with "1" argument(s): "Input string was not in a correct format."

Expected behavior
No errors should occur.

Additional context
Limited debugging statements are included, which made this a bit more tricky to track down.

[TnTBass]

I added some debugging statements in here. They don't cause any harm, but can help identify where any hiccups are occurring if processing multiple folders.