Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

packages/admin/tests/components/EditorHeader.test.tsx

@@ -0,0 +1,75 @@
+import * as React from "react";
+import { describe, it, expect } from "vitest";
+
+import { EditorHeader } from "../../src/components/EditorHeader";
+import { render } from "../utils/render";
+
+describe("EditorHeader", () => {
+	it("renders title content", async () => {
+		const screen = await render(
+			<EditorHeader>
+				<h1>Hello title</h1>
+			</EditorHeader>,
+		);
+		await expect.element(screen.getByRole("heading", { name: "Hello title" })).toBeInTheDocument();
+	});
+
+	it("renders leading content next to the title", async () => {
+		const screen = await render(
+			<EditorHeader leading={<button type="button">Back</button>}>
+				<h1>Title</h1>
+			</EditorHeader>,
+		);
+		await expect.element(screen.getByRole("button", { name: "Back" })).toBeInTheDocument();
+	});
+
+	it("renders actions area for the primary save button", async () => {
+		const screen = await render(
+			<EditorHeader actions={<button type="submit">Save</button>}>
+				<h1>Title</h1>
+			</EditorHeader>,
+		);
+		await expect.element(screen.getByRole("button", { name: "Save" })).toBeInTheDocument();
+	});
+
+	it("applies sticky utility classes by default", async () => {
+		const screen = await render(
+			<EditorHeader actions={<button type="submit">Save</button>}>
+				<h1>Title</h1>
+			</EditorHeader>,
+		);
+		// Locate the wrapper via the data attribute on the root.
+		const wrapper = screen.getByText("Title").element().closest("[data-editor-header]");
+		expect(wrapper).not.toBeNull();
+		expect(wrapper?.classList.contains("sticky")).toBe(true);
+		expect(wrapper?.classList.contains("top-0")).toBe(true);
+	});
+
+	it("omits sticky classes when sticky=false", async () => {
+		const screen = await render(
+			<EditorHeader sticky={false} actions={<button type="submit">Save</button>}>
+				<h1>Title</h1>
+			</EditorHeader>,
+		);
+		const wrapper = screen.getByText("Title").element().closest("[data-editor-header]");
+		expect(wrapper).not.toBeNull();
+		expect(wrapper?.classList.contains("sticky")).toBe(false);
+	});
+
+	it("omits the actions area when no actions prop is provided", async () => {
+		const screen = await render(
+			<EditorHeader>
+				<h1>Just a title</h1>
+			</EditorHeader>,
+		);
+		// The actions container has flex + gap utility classes; assert it
+		// isn't present in the header subtree. Looking at the underlying DOM
+		// avoids relying on global queries that may be affected by leftover
+		// nodes from earlier tests in the shared browser session.
+		const wrapper = screen.getByText("Just a title").element().closest("[data-editor-header]");
+		expect(wrapper).not.toBeNull();
+		// Only one direct child div (the title group) — no actions div.
+		const directChildren = wrapper!.children;
+		expect(directChildren.length).toBe(1);
+	});
+});