improve handling of unexpected toast errors

frontend/src/lib/components/toast.ts

@@ -2,7 +2,11 @@
 const pathRegex = /\b(u|f)\/[^\/\s]+\/[^\/\s]+\b/g
 
 export function processMessage(message: string | undefined): string {
-	return (message ?? 'Error without message').replaceAll(pathRegex, (path) => {
+	return (
+		typeof message == 'string'
+			? message ?? 'Error without message'
+			: JSON.stringify(message, null, 2)
+	).replaceAll(pathRegex, (path) => {
 		return `<span class="bg-surface-secondary p-1 text-xs font-mono whitespace-nowrap rounded-md">${path}</span>`
 	})
 }