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/core/tests/utils/fixtures.ts

@@ -0,0 +1,55 @@
+import type { CreateContentInput } from "../../src/database/repositories/types.js";
+
+/**
+ * Fixture for creating a post
+ */
+export function createPostFixture(overrides: Partial<CreateContentInput> = {}): CreateContentInput {
+	return {
+		type: "post",
+		slug: "hello-world",
+		data: {
+			title: "Hello World",
+			content: [
+				{
+					_type: "block",
+					style: "normal",
+					children: [
+						{
+							_type: "span",
+							text: "This is a test post",
+						},
+					],
+				},
+			],
+		},
+		status: "draft",
+		...overrides,
+	};
+}
+
+/**
+ * Fixture for creating a page
+ */
+export function createPageFixture(overrides: Partial<CreateContentInput> = {}): CreateContentInput {
+	return {
+		type: "page",
+		slug: "about",
+		data: {
+			title: "About",
+			content: [
+				{
+					_type: "block",
+					style: "normal",
+					children: [
+						{
+							_type: "span",
+							text: "About page content",
+						},
+					],
+				},
+			],
+		},
+		status: "draft",
+		...overrides,
+	};
+}