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/marketplace/tests/fixtures/audit/benign-network-usage/backend.js

@@ -0,0 +1,17 @@
+export default {
+	hooks: {
+		"content:beforeSave": async (event, ctx) => {
+			const text = event.content.title + " " + (event.content.excerpt || "");
+			const response = await ctx.http.fetch("https://api.spellcheck.example.com/check", {
+				method: "POST",
+				body: JSON.stringify({ text, lang: "en" }),
+			});
+			const result = await response.json();
+			if (result.corrections?.length > 0) {
+				ctx.log.info(
+					`Found ${result.corrections.length} spelling issues in "${event.content.title}"`,
+				);
+			}
+		},
+	},
+};

packages/marketplace/tests/fixtures/audit/benign-network-usage/expected.json

@@ -0,0 +1 @@
+{ "verdict": "pass", "maxRiskScore": 10, "categories": [] }

packages/marketplace/tests/fixtures/audit/benign-network-usage/manifest.json

@@ -0,0 +1,10 @@
+{
+	"id": "spellcheck",
+	"version": "1.0.0",
+	"capabilities": ["read:content", "network:fetch"],
+	"allowedHosts": ["api.spellcheck.example.com"],
+	"storage": {},
+	"hooks": ["content:beforeSave"],
+	"routes": [],
+	"admin": {}
+}