Fee Recipient POST resulting in key import blocked

[dsimog01]

Describe the bug If a perform a GET request to the /feerecipient endpoint of a validator pubkey that has not been added yet to the client, I obtain a "No validator matching found" message, which is right. However, if a POST request is sent to /feerecipient endpoint of the client API for a validator pubkey that has not been imported yet, the POST is actually performed, but this creates a directory to store that fee recipient address that results in a "DuplicateKeystore" error when trying to import that pubkey.

This means that if you perform a POST request to /feerecipient for a pubkey that has not been added yet, you will never again be able to add it, as far as I understand.

To Reproduce The requests performed are done from Postman while connected to a DAppNode. They are shown below:

Screenshots