I've been trying to get async-export setup for the past day and I've
found it keeps failing due to an unexpected # in the compilation script
generated by org-export.

After doing a little debugging I found the script contained
~(funcall '#<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_77> "foo.tex")~
so at some point in the export org-mode is including an evaluated lambda
when a quoted one is required.

I tracked down the bug to the ~org-latex-export-to-pdf~ function and
fixed it by quoting the unquoted lambda.