Fix build warnings

Changelog-Fixed: Fix build warnings

damus/Models/HomeModel.swift

@@ -154,7 +154,7 @@ class HomeModel {
                 print("nwc: \(resp.req_id) not found in the postbox, nothing to remove [\(relay)]")
             }
             
-            guard let err = resp.response.error else {
+            guard resp.response.error != nil else {
                 print("nwc success: \(resp.response.result.debugDescription) [\(relay)]")
                 nwc_success(state: self.damus_state, resp: resp)
                 return

damus/Util/PostBox.swift

@@ -150,7 +150,7 @@ class PostBox {
             relayer.attempts += 1
             relayer.last_attempt = Int64(Date().timeIntervalSince1970)
             relayer.retry_after *= 1.5
-            if let relay = pool.get_relay(relayer.relay) {
+            if pool.get_relay(relayer.relay) != nil {
                 print("flushing event \(event.event.id) to \(relayer.relay)")
             } else {
                 print("could not find relay when flushing: \(relayer.relay)")