Error talking to user who hasn't added another users

Someone was trying to talk to me without me following them and they got this error:

> error unboxing chat message: This device does not yet have read access to directory /keybase/private/{me},ruipacheco, ask one of the other directory participants to log into Keybase to grant you access automatically: could not find params for uid={foo} device key={bar}
> github.com/keybase/kbfs/libkbfs.(*KeyManagerStandard).getTLFCryptKeyParams
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/key_manager.go:312
> github.com/keybase/kbfs/libkbfs.(*KeyManagerStandard).getTLFCryptKey
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/key_manager.go:156
> github.com/keybase/kbfs/libkbfs.(*KeyManagerStandard).getTLFCryptKeyUsingCurrentDevice
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/key_manager.go:80
> github.com/keybase/kbfs/libkbfs.(*KeyManagerStandard).GetTLFCryptKeyOfAllGenerations
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/key_manager.go:64
> github.com/keybase/kbfs/libkbfs.(*KBFSOpsStandard).GetTLFCryptKeys
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/kbfs_ops.go:412
> github.com/keybase/kbfs/libkbfs.(*KeybaseServiceBase).GetTLFCryptKeys
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/libkbfs/keybase_service_base.go:928
> github.com/keybase/kbfs/vendor/github.com/keybase/client/go/protocol/keybase1.TlfKeysProtocol.func2
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/vendor/github.com/keybase/client/go/protocol/keybase1/tlf_keys.go:194
> github.com/keybase/kbfs/vendor/github.com/keybase/go-framed-msgpack-rpc/rpc.(*callRequest).Serve
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/vendor/github.com/keybase/go-framed-msgpack-rpc/rpc/request.go:76
> github.com/keybase/kbfs/vendor/github.com/keybase/go-framed-msgpack-rpc/rpc.(*receiveHandler).handleReceiveDispatch.func1
> C:/Jenkins/workspace/windows-installer_0/src/github.com/keybase/kbfs/vendor/github.com/keybase/go-framed-msgpack-rpc/rpc/receiver.go:121
> runtime.goexit
> C:/Go/src/runtime/asm_386.s:1629

This issue was created with their permission and the link shared with them.

Start in libkbfs/key_manager.go at getTLFCryptKeyParams and trace the reported call path through kbfs_ops.go and keybase_service_base.go. Reproduce messaging with a user who is not followed, then determine the expected key-access behavior; done means the reported chat error is resolved or the required access limitation is clearly documented.

Written by the indexing model from the issue text.