Added loading and error properties to the query. Inspired by #2089

Author: oliverdowling

libs/dexie-svelte-query/src/lib/stateQuery.svelte.ts

@@ -1,17 +1,28 @@
 import { liveQuery } from "dexie";
 
-export function stateQuery<T>(
-	querier: () => T | Promise<T>,
-	dependencies?: () => unknown[]
-): { current?: T } {
-	const query = $state<{ current?: T }>({ current: undefined });
+export function stateQuery<T>(querier: () => T | Promise<T>, dependencies?: () => unknown[]) {
+	const query = $state<{ current?: T; isLoading: boolean; error?: any }>({
+		current: undefined,
+		isLoading: true,
+		error: undefined,
+	});
 	$effect(() => {
 		dependencies?.();
-		return liveQuery(querier).subscribe((result) => {
-			if (result !== undefined) {
-				query.current = result;
+		return liveQuery(querier).subscribe(
+			(value) => {
+				query.error = undefined;
+				if (value !== undefined) {
+					query.current = value;
+					query.isLoading = false;
+				} else {
+					query.isLoading = true;
+				}
+			},
+			(error) => {
+				query.error = error;
+				query.isLoading = false;
 			}
-		}).unsubscribe;
+		).unsubscribe;
 	});
 	return query;
 }