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/create-emdash/tsdown.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from "tsdown";
+
+export default defineConfig({
+	entry: ["src/index.ts"],
+	format: ["esm"],
+	dts: true,
+	clean: true,
+	banner: {
+		js: "#!/usr/bin/env node",
+	},
+});