Fix unecessary null checks

Author: simolus3

packages/powersync_core/lib/src/database/powersync_db_mixin.dart

@@ -187,7 +187,7 @@ mixin PowerSyncDatabaseMixin implements SqliteConnection {
       if (priority == null) {
         return status.hasSynced == true;
       } else {
-        return status.statusForPriority(priority)?.hasSynced == true;
+        return status.statusForPriority(priority).hasSynced == true;
       }
     }
 

packages/powersync_core/test/in_memory_sync_test.dart

@@ -134,7 +134,7 @@ void main() {
           await expectLater(
             status,
             emits(isSyncStatus(downloading: true, hasSynced: false).having(
-              (e) => e.statusForPriority(BucketPriority(0))?.hasSynced,
+              (e) => e.statusForPriority(BucketPriority(0)).hasSynced,
               'status for $prio',
               isTrue,
             )),
@@ -180,12 +180,12 @@ void main() {
         expect(
             independentDb.currentStatus
                 .statusForPriority(BucketPriority(0))
-                ?.hasSynced,
+                .hasSynced,
             isTrue);
         expect(
             independentDb.currentStatus
                 .statusForPriority(BucketPriority(3))
-                ?.hasSynced,
+                .hasSynced,
             isFalse);
       });
     });