{"record":{"id":"81f3c6402a878820","repo":"emilk/egui","slug":"a-style-should-be-set-for","errorCode":null,"errorMessage":"A style should be set for {:?}","messagePattern":"A style should be set for (.+?)","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/egui/src/theme/themes.rs","lineNumber":51,"sourceCode":"        if !force\n            && self\n                .themes\n                .get_temp::<ThemeWrap<S>>(Id::NULL)\n                .is_some_and(|t| t.lock().type_id() == theme.type_id())\n        {\n            return;\n        }\n\n        self.themes\n            .insert_temp::<ThemeWrap<S>>(Id::NULL, Arc::new(Mutex::new(Box::new(theme))));\n    }\n\n    /// Fetch the style of the current theme\n    pub fn get<S: WidgetStyle + 'static>(&self) -> ThemeWrap<S> {\n        let v = self.themes.get_temp::<ThemeWrap<S>>(Id::NULL);\n\n        v.unwrap_or_else(|| {\n            panic!(\n                \"A style should be set for {:?}\",\n                core::any::type_name::<S>()\n            )\n        })\n    }\n}\n","sourceCodeStart":33,"sourceCodeEnd":58,"githubUrl":"https://github.com/emilk/egui/blob/441971a776322a482e371775219380eca812cfa9/crates/egui/src/theme/themes.rs#L33-L58","documentation":"`Themes::get::<S>()` fetches a widget style (`ThemeWrap<S>`) previously stored via the corresponding `set`. It reads from egui's temp memory keyed by the widget-style type; if no style for type `S` was ever set (or memory was cleared/reset between frames), the lookup returns None and it panics with the type name.","triggerScenarios":"Calling `themes.get::<MyWidgetStyle>()` before ever calling `themes.set::<MyWidgetStyle>(...)`, or after egui memory was reset (e.g. `ctx.memory` clear / new Context instance), so `get_temp::<ThemeWrap<S>>(Id::NULL)` yields None.","commonSituations":"Setting theme styles in one place of the app (e.g. on startup with a feature flag) but reading them unconditionally elsewhere; tests creating a fresh Context without running the set-up path; forgetting the set call after refactoring.","solutions":["Call the matching `themes.set::<MyWidgetStyle>(ThemeWrap::new(...))` before any `get`.","Use the non-panicking lookup (`get_temp` / an `opt` variant) and fall back to a default style when None.","Ensure the `set` runs on the same Context/Themes instance and every frame (temp memory is per-frame for non-persisted temps).","In tests, run the same style-initialization code path as the app before exercising widgets that call `get`."],"exampleFix":"// before\nlet style = themes.get::<ButtonStyle>(); // panics if never set\n// after\nthemes.set::<ButtonStyle>(ThemeWrap::new(ButtonStyle::default()));\nlet style = themes.get::<ButtonStyle>();","handlingStrategy":"fallback","validationCode":"// ensure style exists before get\nif !themes.is_set::<ButtonStyle>() {\n    themes.set::<ButtonStyle>(ThemeWrap::new(ButtonStyle::default()));\n}","typeGuard":"fn style_is_set<S: WidgetStyle + 'static>(themes: &Themes) -> bool {\n    themes.get_temp::<ThemeWrap<S>>(Id::NULL).is_some() // or the crate's opt accessor\n}","tryCatchPattern":null,"preventionTips":["Always call themes.set::<S>(...) during app/Context initialization, unconditionally.","Fall back to S::default() when the style lookup returns None instead of using the panicking get.","Re-run style setup whenever egui memory may be reset (new Context, tests, memory clears).","Cover style initialization in integration tests so a missing set fails early."],"tags":["theme","style","missing-initialization","panic"],"backgroundTag":"missing-configuration","analyzedSha":"441971a776322a482e371775219380eca812cfa9","analyzedAt":"2026-09-12T04:29:21.500Z","contentChangedAt":"2026-09-12T04:29:21.500Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}