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/blocks/playground/vite.config.ts

@@ -0,0 +1,15 @@
+import { fileURLToPath } from "node:url";
+
+import tailwindcss from "@tailwindcss/vite";
+import react from "@vitejs/plugin-react";
+import { defineConfig } from "vite";
+
+export default defineConfig({
+	plugins: [react(), tailwindcss()],
+	resolve: {
+		alias: {
+			// Resolve @emdash-cms/blocks from source for HMR
+			"@emdash-cms/blocks": fileURLToPath(new URL("../src/index.ts", import.meta.url)),
+		},
+	},
+});