Silent failure when keyboxd is not running, no error or warning

[Lee]

Hello, hope you're all doing well!

Today I noticed when trying to list my private keys with 
`--list-secret-keys` that nothing appeared. I was very confused.

After some debugging with `--list-secret-keys --debug-all`, this line 
stood out:

gpg: DBG: chan_4 <- ERR 134217755 Not found <Keybox>

After re-verifying all my secret keys were really there on storage, and 
I had a pubring.kbx, I began to look through `gpg.conf` and `common.conf`.

Behold, there was a `use-keyboxd` there. Deleting this line, I could use 
my keys again.

It would have been really nice for gpg to report the internal error I 
pasted above, as "Unable to communicate with keyboxd", instead of a 
silent failure causing me to have a minor heart palpitation :)

Thank you all for your super hard work on GPG!

Lee