fix build

Author: arthomnix

src/web.rs

@@ -1,19 +1,22 @@
 use crate::FractalViewerApp;
 use wasm_bindgen::prelude::*;
+use web_sys::HtmlCanvasElement;
 
 #[wasm_bindgen(start)]
 async fn wasm_main() -> Result<(), JsValue> {
     console_log::init().expect("error initialising logger");
 
-    let canvas = web_sys::window()
+    let canvas: HtmlCanvasElement = web_sys::window()
         .and_then(|window| window.document())
         .and_then(|document| document.get_element_by_id("fv_canvas"))
-        .expect("Failed to get canvas element!");
+        .expect("Failed to get canvas element!")
+        .dyn_into()
+        .expect("fv_canvas was not an HtmlCanvasElement!");
 
     let runner = eframe::WebRunner::new();
     runner
         .start(
-            canvas.into(),
+            canvas,
             eframe::WebOptions::default(),
             Box::new(|cc| Ok(Box::new(FractalViewerApp::new(cc).unwrap()))),
         )