diff --git a/apps/playground/src/App.tsx b/apps/playground/src/App.tsx
index 1de85ed9..e0e74b71 100644
--- a/apps/playground/src/App.tsx
+++ b/apps/playground/src/App.tsx
@@ -8,6 +8,7 @@ import {
   onCleanup,
 } from 'solid-js';
 import { createStore } from 'solid-js/store';
+import Alert from './components/Alert';
 import Breadcrumbs from './components/Breadcrumbs';
 import Menu from './components/Menu';
 import MonacoEditor from './components/MonacoEditor';
@@ -180,16 +181,11 @@ function App() {
     ]);
   }
 
-  function onDeobfuscateError(error: unknown) {
-    console.error(error);
-  }
-
   return (
     <DeobfuscateContextProvider
       code={activeTab()?.getValue()}
       options={{ ...config }}
       onResult={onDeobfuscateResult}
-      onError={onDeobfuscateError}
     >
       <ProgressBar />
       <Menu
@@ -203,7 +199,6 @@ function App() {
           restoreWorkspace(workspace).catch(console.error);
         }}
       />
-
       <div class="flex" style="height: calc(100vh - 44px)">
         <Sidebar paths={filePaths()} onFileClick={openFile} />
 
@@ -251,6 +246,7 @@ function App() {
           />
         </main>
       </div>
+      <Alert />
     </DeobfuscateContextProvider>
   );
 }
diff --git a/apps/playground/src/components/Alert.tsx b/apps/playground/src/components/Alert.tsx
new file mode 100644
index 00000000..aad4f9e1
--- /dev/null
+++ b/apps/playground/src/components/Alert.tsx
@@ -0,0 +1,53 @@
+import { Show, createEffect, on } from 'solid-js';
+import { useDeobfuscateContext } from '../context/DeobfuscateContext';
+
+export default function Alert() {
+  const { alert, setAlert } = useDeobfuscateContext();
+  let divRef: HTMLDivElement | undefined;
+
+  createEffect(
+    on(alert, () => {
+      divRef?.classList.add('translate-y-96', 'opacity-0');
+      setTimeout(() => {
+        divRef?.classList.remove('translate-y-96', 'opacity-0');
+      }, 0);
+    }),
+  );
+
+  return (
+    <Show when={alert()}>
+      <div
+        ref={divRef}
+        role="alert"
+        class="alert alert-error fixed z-10 max-w-xl m-5 bottom-0 right-0 transition translate-y-96 opacity-0 ease-out duration-500"
+      >
+        <svg
+          xmlns="http://www.w3.org/2000/svg"
+          width="24"
+          height="24"
+          viewBox="0 0 24 24"
+          stroke-width="1.5"
+          stroke="currentColor"
+          fill="none"
+          stroke-linecap="round"
+          stroke-linejoin="round"
+        >
+          <path stroke="none" d="M0 0h24v24H0z" fill="none" />
+          <path d="M12 12m-9 0a9 9 0 1 0 18 0a9 9 0 1 0 -18 0" />
+          <path d="M12 9v4" />
+          <path d="M12 16v.01" />
+        </svg>
+        <span class="break-all">{alert()}</span>
+        <div>
+          <button
+            class="btn btn-sm btn-circle btn-ghost"
+            title="Close"
+            onClick={() => setAlert(null)}
+          >
+            ✕
+          </button>
+        </div>
+      </div>
+    </Show>
+  );
+}
diff --git a/apps/playground/src/context/DeobfuscateContext.tsx b/apps/playground/src/context/DeobfuscateContext.tsx
index c64b407b..806c742d 100644
--- a/apps/playground/src/context/DeobfuscateContext.tsx
+++ b/apps/playground/src/context/DeobfuscateContext.tsx
@@ -13,9 +13,16 @@ let worker = new WebcrackWorker();
 
 const postMessage = (message: WorkerRequest) => worker.postMessage(message);
 
+interface Props {
+  code: string | undefined;
+  options: Options;
+  onResult: (result: DeobfuscateResult) => void;
+}
+
 function useProviderValue(props: Props) {
   const [deobfuscating, setDeobfuscating] = createSignal(false);
   const [progress, setProgress] = createSignal(0);
+  const [alert, setAlert] = createSignal<string | null>(null);
 
   function cancelDeobfuscate() {
     if (!deobfuscating()) return console.warn('Not deobfuscating...');
@@ -43,16 +50,18 @@ function useProviderValue(props: Props) {
           .then((result) => postMessage({ type: 'sandbox', result }))
           .catch((error) => {
             cancelDeobfuscate();
-            props.onError(error);
+            setAlert(String(error));
+            console.error(error);
           });
       } else if (data.type === 'progress') {
         setProgress(data.value);
       } else if (data.type === 'result') {
+        setAlert(null);
         setDeobfuscating(false);
         props.onResult(data);
       } else if (data.type === 'error') {
         setDeobfuscating(false);
-        props.onError(data.error);
+        setAlert(data.error.toString());
       }
     };
   }
@@ -62,18 +71,13 @@ function useProviderValue(props: Props) {
     cancelDeobfuscate,
     deobfuscate,
     progress,
+    alert,
+    setAlert,
   };
 }
 
 const DeobfuscateContext = createContext<ReturnType<typeof useProviderValue>>();
 
-interface Props {
-  code: string | undefined;
-  options: Options;
-  onResult: (result: DeobfuscateResult) => void;
-  onError: (error: unknown) => void;
-}
-
 export function DeobfuscateContextProvider(props: ParentProps<Props>) {
   const value = useProviderValue(props);
   return (
diff --git a/apps/playground/src/monaco/eval-selection.ts b/apps/playground/src/monaco/eval-selection.ts
index ede4d8fc..c4889869 100644
--- a/apps/playground/src/monaco/eval-selection.ts
+++ b/apps/playground/src/monaco/eval-selection.ts
@@ -1,11 +1,14 @@
 import generate from '@babel/generator';
 import * as t from '@babel/types';
 import * as monaco from 'monaco-editor';
+import { useDeobfuscateContext } from '../context/DeobfuscateContext';
 import { evalCode } from '../sandbox';
 
 export function registerEvalSelection(
   editor: monaco.editor.IStandaloneCodeEditor,
 ): monaco.IDisposable {
+  const { setAlert } = useDeobfuscateContext();
+
   const codeAction = monaco.languages.registerCodeActionProvider('javascript', {
     provideCodeActions(_model, range) {
       if (range.isEmpty()) return;
@@ -94,15 +97,20 @@ export function registerEvalSelection(
       return `eval(${JSON.stringify(value)})`;
     });
     const code = `[${expressions.join(',')}]`;
-    const values = (await evalCode(code)) as unknown[];
+    try {
+      const values = (await evalCode(code)) as unknown[];
 
-    const edits = ranges.map((range, index) => ({
-      range,
-      text: mapper(values[index]),
-    }));
+      const edits = ranges.map((range, index) => ({
+        range,
+        text: mapper(values[index]),
+      }));
 
-    editor.pushUndoStop();
-    editor.executeEdits('evaluate-expression', edits);
+      editor.pushUndoStop();
+      editor.executeEdits('evaluate-expression', edits);
+      setAlert(null);
+    } catch (error) {
+      setAlert(`${String(error)}, at ${ranges.join(', ')}`);
+    }
   }
 
   return {
diff --git a/apps/playground/src/webcrack.worker.ts b/apps/playground/src/webcrack.worker.ts
index 9e4cd4ba..74e04f5b 100644
--- a/apps/playground/src/webcrack.worker.ts
+++ b/apps/playground/src/webcrack.worker.ts
@@ -9,7 +9,7 @@ export type WorkerResponse =
   | { type: 'sandbox'; code: string }
   | ({ type: 'result' } & DeobfuscateResult)
   | { type: 'progress'; value: number }
-  | { type: 'error'; error: unknown };
+  | { type: 'error'; error: Error };
 
 export interface DeobfuscateResult {
   code: string;
@@ -53,6 +53,6 @@ self.onmessage = async ({ data }: MessageEvent<WorkerRequest>) => {
 
     postMessage({ type: 'result', code: result.code, files });
   } catch (error) {
-    postMessage({ type: 'error', error });
+    postMessage({ type: 'error', error: error as Error });
   }
 };