Unhandled exception: Null check operator used on a null value

# get generate model on home with assets/models/server.json

Unhandled exception:
Null check operator used on a null value
#0 PubspecUtils.nullSafeSupport (package:get_cli/common/utils/pubspec/pubspec_utils.dart:146:76)
#1 new TypeDefinition (package:get_cli/common/utils/json_serialize/sintaxe.dart:81:22)
#2 new TypeDefinition.fromDynamic (package:get_cli/common/utils/json_serialize/sintaxe.dart:68:12)
#3 ModelGenerator._generateClassDefinition (package:get_cli/common/utils/json_serialize/model_generator.dart:68:36)
#4 ModelGenerator.generateUnsafeDart (package:get_cli/common/utils/json_serialize/model_generator.dart:148:9)
#5 ModelGenerator.generateDartClasses (package:get_cli/common/utils/json_serialize/model_generator.dart:181:28)
#6 GenerateModelCommand.execute (package:get_cli/commands/impl/generate/model/model.dart:41:35)

#7 main. (file:///Users/faiz/.pub-cache/hosted/pub.dev/get_cli-1.9.1/bin/get.dart:18:38)

#8 main (file:///Users/faiz/.pub-cache/hosted/pub.dev/get_cli-1.9.1/bin/get.dart:18:9)