It mentions that there has been an issue translating a Unicode character:
ERROR: AutomationTool terminated with exception: System.Text.EncoderFallbackException: Unable to translate Unicode character \uDDDD at index 46 to specified code page.
Have you used any symbols such as !, @, #, etc or any languages such as Cyrillic that have their own alphabets/symbols in your project? If so, could you try replacing those and see if that resolves the issue? Depending on the circumstances they still may be usable but it would be best to narrow down where the failure is coming from.
The first thing I did was go through and remove two + that were in an append node. I also took out any and all float, int, string, conversions going either way. I rolled back the repo to an earlier commit that packaging had worked and got the same result.
Eventually I deleted and recloned the repo, reinstalled the engine and plugins and it all worked. Something must have gotten corrupted somewhere.