merge: Bridged error message for when you try search for a post and it fails (!421)

View MR for information: https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/421

Approved-by: dakkar <dakkar@thenautilus.net>
Approved-by: Marie <marie@kaifa.ch>

packages/frontend/src/os.ts

@@ -108,12 +108,19 @@ export function promiseDialog<T extends Promise<any>>(
 		showing.value = false;
 		if (onFailure) {
 			onFailure(err);
+		} else {
+			if (err.message) {
+				alert({
+					type: 'error',
+					text: err.message,
+				});
 			} else {
 				alert({
 					type: 'error',
 					text: err,
 				});
 			}
+		}
 	});
 
 	// NOTE: dynamic importすると挙動がおかしくなる(showingの変更が伝播しない)