Warn instead of error when stash import user does not exist.

src/tools/stashes-load.js

@@ -120,7 +120,8 @@ async function load() {
 			.first();
 
 		if (!user) {
-			throw new Error(`No user '${stash.username}'`);
+			console.warn(`No user '${stash.username}'`);
+			return;
 		}
 
 		const stashId = await getStashId(stash, user);