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/fields/image.test.ts

@@ -0,0 +1,64 @@
+import { describe, it, expect } from "vitest";
+
+import { image } from "../../src/fields/image.js";
+
+describe("image field", () => {
+	it("should create field definition", () => {
+		const field = image();
+
+		expect(field.type).toBe("image");
+		expect(field.schema).toBeDefined();
+		expect(field.ui?.widget).toBe("image");
+	});
+
+	it("should accept valid image value", () => {
+		const field = image();
+		const valid = {
+			id: "img-123",
+			src: "https://example.com/image.jpg",
+			alt: "Test image",
+			width: 800,
+			height: 600,
+		};
+
+		expect(() => field.schema.parse(valid)).not.toThrow();
+	});
+
+	it("should accept image without optional fields", () => {
+		const field = image();
+		const minimal = {
+			id: "img-123",
+			src: "https://example.com/image.jpg",
+		};
+
+		expect(() => field.schema.parse(minimal)).not.toThrow();
+	});
+
+	it("should reject invalid image value", () => {
+		const field = image();
+
+		expect(() => field.schema.parse({ id: "missing-src" })).toThrow();
+		expect(() => field.schema.parse("not an object")).toThrow();
+	});
+
+	it("should support required option", () => {
+		const required = image({ required: true });
+		const optional = image({ required: false });
+
+		// Required should reject undefined
+		expect(() => required.schema.parse(undefined)).toThrow();
+
+		// Optional should accept undefined
+		expect(() => optional.schema.parse(undefined)).not.toThrow();
+	});
+
+	it("should store options", () => {
+		const field = image({
+			maxSize: 5 * 1024 * 1024, // 5MB
+			allowedTypes: ["image/jpeg", "image/png"],
+		});
+
+		expect(field.options?.maxSize).toBe(5 * 1024 * 1024);
+		expect(field.options?.allowedTypes).toEqual(["image/jpeg", "image/png"]);
+	});
+});