Cannot send the first message in a conversation: 404 not found

New contacts provision their pre-keys on the UUID path (/v2/keys/UUID), instead of on E164-basis (/v2/keys/+32...). This makes WF unable to send messages to devices registered with an official client after about Februari 2021.

Resolution

We resolve this in two steps.

1. After #80 (closed), the other Signal user will be able to initiate the session. After this, we have a workaround.
2. We need Signal profiles (#192 (closed)), at least partially, to fully resolve this issue, because those resolve the UUID for a given E164.