BadValsizeError (MBD_BAD_VALSIZE) error thrown when resolving a slightly incorrect oobi url

[daidoji]

Not a big issue but I noticed that when I

1. Started the witness demo kli witness demo
2. Then retrieved the incorrect url http://127.0.0.1:5642/oobi/ (notice the trailing slash that shouldn't be there)

I'd get a traceback Falcon error as below.

Ran this between the demo command and the traceback below. daidoji@darkstar:~$ curl http://127.0.0.1:5642/oobi/

(keri) daidoji@darkstar:~/ssi/keripy$ kli witness demo &
[1] 31993
(keri) daidoji@darkstar:~/ssi/keripy$ Witness wan : BBilc4-L3tFUnfM_wJr4S4OJanAv_VmF_dJNN6vkf2Ha
Witness wil : BLskRTInXnMxWaGqcpSyMgo0nYbalW99cGZESrz3zapM
Witness wes : BIKKuvBwpmDVA4Ds-EpL5bt9OqPzWPja2LigFYZN2YfX
Witness wit : BM35JN8XeJSEfpxopjn5jr7tAHCE5749f0OobhMLCorE
Witness wub : BIj15u5V11bkbtAxMA7gcNJZcax-7TgaBMLsQnMHpYHP
Witness wyz : BF2rZTW79z4IXocYRQnjjsOuvFUQv-ptCf8Yltd7PfsM
2023-09-26 09:44:16 [FALCON] [ERROR] GET /oobi/ => Traceback (most recent call last):
  File "/home/daidoji/ssi/keripy/src/keri/db/basing.py", line 62, in __getitem__
    return super(dbdict, self).__getitem__(k)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: ''

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "falcon/app.py", line 365, in falcon.app.App.__call__
  File "/home/daidoji/ssi/keripy/src/keri/end/ending.py", line 571, in on_get
    if aid not in self.hby.kevers:
       ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daidoji/ssi/keripy/src/keri/db/basing.py", line 78, in __contains__
    self.__getitem__(k)
  File "/home/daidoji/ssi/keripy/src/keri/db/basing.py", line 66, in __getitem__
    if (ksr := self.db.states.get(keys=k)) is None:
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daidoji/ssi/keripy/src/keri/db/koming.py", line 281, in get
    return (self.deserializer(self.db.getVal(db=self.sdb,
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daidoji/ssi/keripy/src/keri/db/dbing.py", line 449, in getVal
    return( txn.get(key))
            ^^^^^^^^^^^^
lmdb.BadValsizeError: mdb_get: MDB_BAD_VALSIZE: Unsupported size of key/DB name/data, or wrong DUPFIXED size

Seems to be caused by a root issue with empty keys in LMDB and LMDBer when I walked through the code.