Fix some warnings

examples/hello_world_par/src/main.rs

@@ -100,7 +100,7 @@ impl MyApp {
         let threads = Vec::with_capacity(3);
         let (on_done_tx, on_done_rc) = mpsc::sync_channel(0);
 
-        let mut slf = Self {
+        let slf = Self {
             data: Arc::new(RwLock::new(MyAppData {
                 threads,
                 on_done_tx,

examples/viewports/src/main.rs

@@ -2,12 +2,10 @@ use eframe::egui;
 use eframe::egui::Id;
 use eframe::NativeOptions;
 
-use std::sync::{Arc, RwLock};
-
 fn main() {
     env_logger::init(); // Use `RUST_LOG=debug` to see logs.
 
-    eframe::run_simple_native(
+    let _ = eframe::run_simple_native(
         "Viewports Examples",
         NativeOptions {
             renderer: eframe::Renderer::Wgpu,