eythaann/Seelen-UI · error · Error

Missing webview label

Error message

Missing webview label

What it means

`WebviewInformation.rawLabel` reads the webview label from Tauri internals (`window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label`). It throws `Missing webview label` when the label is absent, meaning the code is not running inside a properly initialized Tauri webview or Tauri internals were not injected.

Source

Thrown at src/ui/vanilla/entry-point/_tauri.ts:11

// this file is used to reduce bundle size on widget loader, to mantain the minimal bundle size possible
// this file can't use dependencies
import type { InvokeArgs, InvokeOptions } from "@tauri-apps/api/core";

class WebviewInformation {
  _label: string | null = null;

  get rawLabel() {
    let label = window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label;
    if (!label) {
      throw new Error("Missing webview label");
    }
    return label;
  }

  get label() {
    if (this._label) {
      return this._label;
    }

    const viewLabel = window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label;
    this._label = viewLabel ? decodeUrlSafeBase64(viewLabel) : "Unknown";
    return this._label;
  }

  get widgetId() {
    const [id, _] = this.label.split("?");
    if (!id) {
      throw new Error("Invalid widget id");

View on GitHub (pinned to dee4aaa940)

Solutions

1. Run the code inside a Tauri webview (via Seelen UI / `npm run tauri dev`), not a plain browser.
2. Mock `window.__TAURI_INTERNALS__.metadata.currentWebview.label` in tests/browser previews.
3. Check your Tauri version's internals path; adapt the lookup if `metadata.currentWebview` moved.

Example fix

// before
let label = window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label;
// after (defensive access with mock support)
let label = window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label
  ?? window.__MOCK_WEBVIEW_LABEL__;

if (typeof window === "undefined" || !window.__TAURI_INTERNALS__?.metadata?.currentWebview) {
  // not inside a Tauri webview — skip Tauri-dependent bootstrap
}

function inTauriWebview(): boolean {
  return typeof window !== "undefined"
    && !!window.__TAURI_INTERNALS__?.metadata?.currentWebview?.label;
}

let label: string;
try {
  label = webviewInfo.rawLabel;
} catch (e) {
  if ((e as Error).message === "Missing webview label") {
    label = "dev-fallback"; // browser/test environment
  } else throw e;
}

When it happens

Trigger: Running the frontend bundle in a plain browser / dev server where `__TAURI_INTERNALS__` is undefined; using an old or custom Tauri runtime where the `metadata.currentWebview` structure changed; accessing `rawLabel` before Tauri's initialization script ran.

Common situations: Opening the widget UI via `npm run dev`/browser preview instead of inside the Seelen UI webview; Tauri version upgrade renaming internals; unit tests rendering the module in jsdom without a Tauri mock.

Related errors

• The library is being used on a non Seelen UI environment
• Missing widget id on webview label
• Root element not found
• Widget definition not found for ${currentWidgetId}
• Invalid widget id

AI-assisted analysis of eythaann/Seelen-UI@dee4aaa940 (2026-09-03). Data as JSON: /api/errors/cc6bc0b981c6e65f. Report an issue: GitHub.