Flutter: pub finished with exit code 255

Question

I am making models for my flutter application via build runner,json model and json serializable. But i got this error

Unhandled exception:
RangeError (index): Invalid value: Valid value range is empty: 0
#0      _StringBase.[] (dart:core-patch/string_patch.dart:247:55)
#1      changeFirstChar (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:89:41)
#2      getType (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:116:20)
#3      walk.<anonymous closure>.<anonymous closure> (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:62:23)
#4      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8)
#5      walk.<anonymous closure> (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:50:37)
#6      List.forEach (dart:core-patch/growable_array.dart:282:8)
#7      walk (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:38:8)
#8      main (file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/json_model-0.0.2/bin/json_model.dart:18:6)
#9      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:299:32)
#10     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
pub finished with exit code 255

In my pubspec.yaml file i added these flutter packages in dev dependencies:

dev_dependencies:
  flutter_test:
    sdk: flutter
  json_model: ^0.0.2
  json_serializable:
  build_runner:

My Json files for which i want to make models:

1st json file

{
  "id": 1,
  "country": "Australia",
  "currencySymbol": "$"
}

2nd Json file

{
  "currencylist": "$[]currency"
}

Can you please help me where i am doing wrong in this and why i am getting this error when i run command in terminal flutter packages pub run json_model.

Answer 1

this is too late but someone might get use of it, this worked for me:

I think this might happen when you change something in your model and you run agin

flutter pub run build_runner build

update:

run this and it will do the job for you:

flutter pub run build_runner build  --delete-conflicting-outputs 

old : so first try to delete all generated files that ends with

XXX.g.dart

and run

flutter clean 

then

flutter pub get

Finally

flutter pub run build_runner build

Answer 2

You can simple run the

1.flutter clean.
2.flutter pub get.

This saves my several hours.