Error when there are no translation strings for the language

[Holofox]

Reproduction steps:

1. Create a project, add any language, do nothing else.
2. Get localization via API flutter pub run arbify:download.

Output directory doesn't exist. Creating... done.
Unhandled exception:
type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>' in type cast
#0      ArbifyApi.fetchAvailableExports.<anonymous closure> (package:arbify/src/api/arbify_api.dart:27:29)
#1      _RootZone.runUnary (dart:async/zone.dart:1450:54)
#2      _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
#3      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
#4      Future._propagateToListeners (dart:async/future_impl.dart:725:32)
#5      Future._complete (dart:async/future_impl.dart:519:7)
#6      _SyncCompleter.complete (dart:async/future_impl.dart:55:12)
#7      Future.any.onValue (dart:async/future.dart:473:45)
#8      _RootZone.runUnary (dart:async/zone.dart:1450:54)
#9      _FutureListener.handleValue (dart:async/future_impl.dart:143:18)
#10     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:696:45)
#11     Future._propagateToListeners (dart:async/future_impl.dart:725:32)
#12     Future._completeWithValue (dart:async/future_impl.dart:529:5)
#13     _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:40:15)
#14     _completeOnAsyncReturn (dart:async-patch/async_patch.dart:311:13)
#15     DioMixin._dispatchRequest (package:dio/src/dio.dart)
<asynchronous suspension>
#16     DioMixin._request._interceptorWrapper.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:dio/src/dio.dart:849:37)
#17     DioMixin.checkIfNeedEnqueue (package:dio/src/dio.dart:1121:22)
#18     DioMixin._request._interceptorWrapper.<anonymous closure>.<anonymous closure> (package:dio/src/dio.dart:846:22)
#19     new Future.<anonymous closure> (dart:async/future.dart:175:37)
#20     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
#21     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:397:19)
#22     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:428:5)
#23     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
pub finished with exit code 255