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/unit/db/dialect-runtime-imports.test.ts

@@ -0,0 +1,48 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+
+import { describe, expect, it } from "vitest";
+
+/**
+ * Regression test for #741 ("Cannot find module 'kysely'" after build).
+ *
+ * The dialect runtime modules (db/sqlite.ts, db/libsql.ts, db/postgres.ts)
+ * are bundled into the user's site dist via `noExternal: ["emdash"]` in
+ * the Astro integration's Vite SSR config. If any of them uses CJS
+ * `require("kysely")` (or another external) instead of a static `import`,
+ * the bundler emits a literal `require("kysely")` call into the user's
+ * dist chunks. At runtime under pnpm's strict node_modules layout, that
+ * `require()` resolves from the user's `dist/server/chunks/` directory,
+ * walks up looking for `node_modules/kysely`, doesn't find it (because
+ * kysely is only a transitive dep of `emdash`), and throws
+ * `MODULE_NOT_FOUND`.
+ *
+ * Static `import`s let Vite either externalize the dep correctly or pull
+ * it into the bundle. Either outcome resolves at runtime; the dynamic
+ * `require()` form does not. Keep these files static-import-only.
+ */
+describe("dialect runtime modules", () => {
+	const dialectFiles = [
+		fileURLToPath(new URL("../../../src/db/sqlite.ts", import.meta.url)),
+		fileURLToPath(new URL("../../../src/db/libsql.ts", import.meta.url)),
+		fileURLToPath(new URL("../../../src/db/postgres.ts", import.meta.url)),
+	];
+
+	for (const file of dialectFiles) {
+		it(`${file.split("/db/")[1]} does not use require() to load externals`, () => {
+			const source = readFileSync(file, "utf-8");
+			// Strip line comments (`//`), block comments (`/* … */`), and string
+			// literals before scanning. We only care about actual code-level
+			// `require(` calls; a docstring or inline comment that mentions
+			// the historical bug should not trip the assertion.
+			const codeOnly = source
+				.replace(/\/\*[\s\S]*?\*\//g, "")
+				.replace(/(^|[^:])\/\/.*$/gm, "$1")
+				.replace(/(["'`])(?:\\.|(?!\1).)*\1/g, '""');
+			// Any standalone require( call in these files re-introduces the
+			// bug: the bundler leaves it as-is, and runtime resolution under
+			// pnpm fails for transitive deps like `kysely`.
+			expect(codeOnly).not.toMatch(/(?<![.\w])require\s*\(/);
+		});
+	}
+});