Rename error boundary hook

It doesn't check whether it's actually used inside a GroupCallErrorBoundary, and it's generally useful for interacting with any error boundary, so I'm giving it a generic name to reflect this.

src/useErrorBoundary.test.tsx

@@ -0,0 +1,51 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { it, vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { type ReactElement, useCallback } from "react";
+import userEvent from "@testing-library/user-event";
+import { BrowserRouter } from "react-router-dom";
+
+import { GroupCallErrorBoundary } from "./room/GroupCallErrorBoundary";
+import { useErrorBoundary } from "./useErrorBoundary";
+import { ConnectionLostError } from "./utils/errors";
+
+it("should show async error", async () => {
+  const user = userEvent.setup();
+
+  const TestComponent = (): ReactElement => {
+    const { showErrorBoundary } = useErrorBoundary();
+
+    const onClick = useCallback((): void => {
+      showErrorBoundary(new ConnectionLostError());
+    }, [showErrorBoundary]);
+
+    return (
+      <div>
+        <h1>HELLO</h1>
+        <button onClick={onClick}>Click me</button>
+      </div>
+    );
+  };
+
+  render(
+    <BrowserRouter>
+      <GroupCallErrorBoundary widget={null} recoveryActionHandler={vi.fn()}>
+        <TestComponent />
+      </GroupCallErrorBoundary>
+    </BrowserRouter>,
+  );
+
+  await user.click(screen.getByRole("button", { name: "Click me" }));
+
+  await screen.findByText("Connection lost");
+
+  await user.click(screen.getByRole("button", { name: "Reconnect" }));
+
+  await screen.findByText("HELLO");
+});