The double quotes didn't work, but using:
does something kind of odd?
It throws an error 88 (like everything else I've tried does), but instead of saying "Exception occurred (err/ret=2/0)" it says something new (to me):
"The server threw an exception (err/ret=2/0)"
If I try the same line 2 or 3 more times, it eventually works! It doesn't seem to be lag from creating the table_cache in the previous line. I sat waiting at the create pivot table line for a couple minutes once, and still had to retry it three times before it magically worked.
I'd bandage it with an err=*same but I don't think you can do that with LET statements...