{"record":{"id":"9f5c62f0e596becb","repo":"iced-rs/iced","slug":"get-window-canvas","errorCode":null,"errorMessage":"Get window canvas","messagePattern":"Get window canvas","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"critical","filePath":"winit/src/lib.rs","lineNumber":348,"sourceCode":" let mut window_attributes = window_attributes;\n\n #[cfg(target_os = \"macos\")]\n let position = window_attributes.position.take();\n\n let window = event_loop\n .create_window(window_attributes)\n .expect(\"Create window\");\n\n #[cfg(target_os = \"macos\")]\n if let Some(position) = position {\n window.set_outer_position(position);\n }\n\n #[cfg(target_arch = \"wasm32\")]\n {\n use winit::platform::web::WindowExtWebSys;\n\n let canvas = window.canvas().expect(\"Get window canvas\");\n\n let _ = canvas.set_attribute(\n \"style\",\n \"display: block; width: 100%; height: 100%\",\n );\n\n let window = web_sys::window().unwrap();\n let document = window.document().unwrap();\n let body = document.body().unwrap();\n\n let target = target.and_then(|target| {\n body.query_selector(&format!(\"#{target}\"))\n .ok()\n .unwrap_or(None)\n });\n\n match target {\n Some(node) => {","sourceCodeStart":330,"sourceCodeEnd":366,"githubUrl":"https://github.com/iced-rs/iced/blob/d146509d893945de5c304cfaf4301335eee278bd/winit/src/lib.rs#L330-L366","documentation":"On wasm32 targets, the winit runtime calls window.canvas() (WindowExtWebSys) and expects it to return Some. winit's web backend returns None when the browser window has no valid canvas element to associate with the WebGL/WebGPU context (e.g. the Window was created from a closed/invalid context or the DOM state is unexpected).","triggerScenarios":"Running an iced wasm app where event_loop.create_window succeeds but window.canvas() returns None - typically when the HTML page lacks the expected canvas setup or the window was obtained in a worker/off-screen context.","commonSituations":"Serving the app from an HTML template missing the