This is usually a divide by zero or divide by invalid character problem.
If this problem happens again, I would like to find out what is causing it.  If you would like to, run the script using the 
-dump and you should get an email filled with attachments.  If you could forward that email and attachments to 
joeschmuck2023@hotmail.com then I would have the same data as the -dump email.  If you can get the attachments, then I'm not sure why the '-dump email' command does not work.  Just to make sure you are entering the command correctly, it is: 
multi_report.sh -dump email, assuming you named the script 'multi_report.sh'.
That is the correct current version.  I plan to push another update in August to fix a few little things.  If you are still having this issue, I'd like to see if I can include that fix as well.  But hopefully it was a one time issue.  If you still have this, I suspect some drive value is not in the correct location on the SMART output, it happens all too frequently.