test: remove invalid null check

test/search/setup_database_connection.dart

@@ -20,9 +20,5 @@ Future<Database> setup_database_connection() async {
     jadbPath: jadb_path,
   );
 
-  if (db_connection == null) {
-    throw Exception("Failed to open database");
-  }
-
   return db_connection;
 }