Fix initial paint of web app (#5633)

* Broke in #5631 (for _some_ apps)

crates/eframe/src/web/events.rs

@@ -890,7 +890,7 @@ impl ResizeObserverContext {
             let runner_ref = runner_ref.clone();
             move |entries: js_sys::Array| {
                 if DEBUG_RESIZE {
-                    // log::info!("ResizeObserverContext callback");
+                    log::info!("ResizeObserverContext callback");
                 }
                 // Only call the wrapped closure if the egui code has not panicked
                 if let Some(mut runner_lock) = runner_ref.try_lock() {
@@ -919,6 +919,8 @@ impl ResizeObserverContext {
                     if let Err(err) = runner_ref.request_animation_frame() {
                         log::error!("{}", super::string_from_js_value(&err));
                     };
+                } else {
+                    log::warn!("ResizeObserverContext callback: failed to lock runner");
                 }
             }
         }) as Box<dyn FnMut(js_sys::Array)>);

crates/eframe/src/web/web_runner.rs

@@ -71,24 +71,27 @@ impl WebRunner {
             canvas.style().set_property("outline", "none")?;
         }
 
-        let text_agent = TextAgent::attach(self)?;
+        {
+            // First set up the app runner:
+            let text_agent = TextAgent::attach(self)?;
+            let app_runner =
+                AppRunner::new(canvas.clone(), web_options, app_creator, text_agent).await?;
+            self.app_runner.replace(Some(app_runner));
+        }
 
         {
             let resize_observer = events::ResizeObserverContext::new(self)?;
 
-            // This will (eventually) result in a `request_animation_frame` to start the render loop.
+            // Properly size the canvas. Will also call `self.request_animation_frame()` (eventually)
             resize_observer.observe(&canvas);
 
             self.resize_observer.replace(Some(resize_observer));
         }
 
-        {
-            let app_runner = AppRunner::new(canvas, web_options, app_creator, text_agent).await?;
-            self.app_runner.replace(Some(app_runner));
-        }
-
         events::install_event_handlers(self)?;
 
+        log::info!("event handlers installed.");
+
         Ok(())
     }