chore: satisfy clippy 1.99

CI's Lint job runs current stable, which gained two lints that failed
develop: `redundant_else` in `Client::login`, now written with early
returns, and `assert_is_empty`, which asks every `assert!(x.is_empty())`
in the tests to become `assert_eq!(x, [] as [T; 0])`. The second trades a
clear check for a type-cast chore, so it joins the curated allow-list.

Cargo.toml

@@ -53,6 +53,9 @@ significant_drop_tightening = "allow"
 # Subjective nursery lint: the suggested map_or/map_or_else rewrites read worse
 # than the explicit if let/match they replace.
 option_if_let_else = "allow"
+# `assert!(x.is_empty())` in tests is fine; the suggested
+# `assert_eq!(x, [] as [T; 0])` only trades a clear check for a type-cast chore.
+assert_is_empty = "allow"
 # The MD5 round functions use the conventional a/b/c/d register names from the
 # RFC 1321 reference implementation.
 many_single_char_names = "allow"

soulseek-rs-lib/src/client/connection.rs

@@ -209,9 +209,12 @@ impl Client {
     /// control.
     pub fn login(&self) -> Result<bool> {
         info!("Logging in as {}", self.username);
-        if let Some(handle) = &self.server_handle
-            && !self.cancel.is_cancelled()
-        {
+        let Some(handle) = &self.server_handle else {
+            return Err(SoulseekRs::NotConnected);
+        };
+        if self.cancel.is_cancelled() {
+            return Err(SoulseekRs::NotConnected);
+        }
         let (tx, rx) = std::sync::mpsc::channel();
         let _ = handle.send(ServerMessage::Login {
             username: self.username.clone(),
@@ -229,14 +232,11 @@ impl Client {
                 {
                     return Err(SoulseekRs::NotConnected);
                 }
-                    Err(RecvTimeoutError::Timeout)
-                        if Instant::now() < deadline => {}
+                Err(RecvTimeoutError::Timeout) if Instant::now() < deadline => {
+                }
                 Err(_) => return Err(SoulseekRs::Timeout),
             }
         }
-        } else {
-            Err(SoulseekRs::NotConnected)
-        }
     }
 
     /// Ask the server for a peer's address and open a direct control