Validator Client Unable to Find Index for Public Key

[nisdas]

When running the validator client with the following command :

/path/to/validator/client --beacon-rpc-provider http://localhost:4000 --datadir /path/to/validator/db --pubkey AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

the following error log shows up

[2018-11-22 13:31:52] ERROR beacon: Could not receive latest validator assignment from stream: rpc error: code = Unknown desc = could not get assignments for public keys: can't find validator index for public key 0x414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141

This only started appearing after #875 and #870 were merged in.