bug#47941: guix lint -c cve stacktrace

[Jack Hill]

Hi Guix,

Using guix ae5128e21eb7afa66bd7cfd7fd1bc5764d00663e, the cve lint check 
fails when fetching the CVE database as follows:

$ guix lint -c cve hello
fetching CVE database for 2021...
Backtrace:
          15 (primitive-load "/home/jackhill/.config/guix/current/bi…")
In guix/ui.scm:
  2164:12 14 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1736:10 13 (with-exception-handler _ _ #:unwind? _ # _)
  1731:15 12 (with-exception-handler #<procedure 7f895ab7d000 at ic…> …)
In srfi/srfi-1.scm:
    634:9 11 (for-each #<procedure 7f895ab84d80 at guix/scripts/lin…> …)
In guix/scripts/lint.scm:
     65:4 10 (run-checkers _ _ #:store _)
In srfi/srfi-1.scm:
    634:9  9 (for-each #<procedure 7f895420bc00 at guix/scripts/lin…> …)
In guix/scripts/lint.scm:
    74:21  8 (_ _)
In guix/lint.scm:
   1178:4  7 (check-vulnerabilities _ _)
   1170:9  6 (_ _)
In unknown file:
           5 (force #<promise #<procedure 7f895af13a88 at guix/lint.…>)
In guix/lint.scm:
   1153:2  4 (_)
   1112:2  3 (call-with-networking-fail-safe _ _ _)
In ice-9/boot-9.scm:
  1736:10  2 (with-exception-handler _ _ #:unwind? _ # _)
  1669:16  1 (raise-exception _ #:continuable? _)
  1667:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1667:16: In procedure raise-exception:
Wrong type (expecting array): #f

Best,
Jack