`fetch': key not found: "data" (KeyError) #60

{
  "__schema": {
    "queryType": {
      "name": "QueryRoot"
    },
    "mutationType": {
      "name": "Mutation"
    },
    "subscriptionType": null,
    "types": ...,
    "directives": ...,
  }
}

require 'graphql_schema'
require 'graphql_java_gen'
require 'json'

introspection_result = File.read("shopify-admin.json")
schema = GraphQLSchema.new(JSON.parse(introspection_result))

GraphQLJavaGen.new(schema,
  package_name: "com.example.MyApp",
  nest_under: 'ExampleSchema',
  version: '2022-01',
  custom_scalars: [
    GraphQLJavaGen::Scalar.new(
      type_name: 'Decimal',
      java_type: 'BigDecimal',
      deserialize_expr: ->(expr) { "new BigDecimal(jsonAsString(#{expr}, key))" },
      imports: ['java.math.BigDecimal'],
    ),
  ]
).save("#{Dir.pwd}/../MyApp/src/main/java/com/example/MyApp/ExampleSchema.java")

khaled@khaleds-mbp graphql_java_gen-master % ruby example.ruby                                                            
Traceback (most recent call last):
	3: from example.ruby:6:in `<main>'
	2: from example.ruby:6:in `new'
	1: from /Library/Ruby/Gems/2.6.0/gems/graphql_schema-0.1.8/lib/graphql_schema.rb:6:in `initialize'
/Library/Ruby/Gems/2.6.0/gems/graphql_schema-0.1.8/lib/graphql_schema.rb:6:in `fetch': key not found: "data" (KeyError)