Right now, if ttrss makes a request for a URL that we don't already have a capability for, and the proxy does not have an open connection to a client, it will simply return an error.
This is problematic in that it can cause requests to fail if they come in as the app is booting up, if the client hasn't yet had a chance to connect.
Instead, we should block until a connection is available, or the request times out.
Right now, if ttrss makes a request for a URL that we don't already have a capability for, and the proxy does not have an open connection to a client, it will simply return an error.
This is problematic in that it can cause requests to fail if they come in as the app is booting up, if the client hasn't yet had a chance to connect.
Instead, we should block until a connection is available, or the request times out.